1) There is a hard and fast distinction based on a sacramental and therefore ontological difference between sharing in Christ the Priest as Body and sharing in the Christ the Priest as Head. The terminology for this distinction is “lay faithful” and “minister” respectively. See Lumen gentium #10.
2) The document “Ministeria Quaedam” (15 August, 1972) blurred that essential difference by transposing to the lay faithful “the functions of the subdiaconate,” pace its intention to the contrary.
John Paul II and the Synod Christifideles laici saw the need to revisit that confusion. It was done in 1994 and in 1997.
The commonality of laity and priests as “People of God" is priesthood, not ministry. The entire people of God are such because they share in the one priesthood of Christ.
3) Ministry is a term reserved for that sharing in the priesthood of Christ that acts in His Person as Head and Shepherd of the Church. "Ministry" refers to an ontologically distinct way of being priest from the lay faithful: "The relation of the priest to Jesus Christ, and in him to his Church, is found in the very being of the priest by virtue of his sacramental consecration/anointing and in his activity, that is, in his mission or ministry" (Pastores Dabo Vobis #16).
4) The distinction between common priesthood (laity) and ministers is not a historical development but sacramental from the beginning. Christ instituted Baptism and Orders thereby distinguishing two (2) essentially different ways of exercising his priesthood (mediation). These two essentially different ways correspond to two distinct parts of the analogy of Body in Christ. Ministry pertains to the Head; laity pertains to members. These morphological parts of the analogy of the Body correspond to the spousal distinction between Bridegroom (Head) and Bride (Members). The Body that is the Church is the Bride, that has Mary as Prototype. The Head that is Bridegroom is Christ. The difference is sacramental establishing “indelible character” in each, and therefore of an ontological nature. The Church of Mary (laity) takes precedence over the Church of Peter.
Therefore, laymen and women are priests as mediators primarily to the world and secondarily to the Church in ministries. They are never ministers. Women are incapable of Orders that would ontologically establish them as acting in the Person of the Bridegroom and Good Shepherd (Pastor) who gives up his life for his Bride/Sheep.
5) To blur the distinction between mission and ministry, and ministry and minister creates a confusion that betrays the received teaching of the Magisterium and constitutes a “novelty.” As novelty it is a departure from Magisterial teaching. It concludes by clericalizing the laity and laicizing the clergy to the detriment of both Church and Civil Society.
6)There is the de facto establishment of elitism among the laity, despite the document's disclaimers to the contrary, and therefore a dualism of a perceived “ordained laity”  distinct from the mere common laity. This confusion will quicken the decrease of vocations to the ministerial priesthood.
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 “Christ the Lord, high priest taken from among men (cf. Heb. 5, 1-5), made the new people `a kingdom of priests to God, his Father.’ The baptized… are consecrated to be a spiritual house and a holy priesthood…
“Though they differ essentially and not only in degree, the common priesthood of the faithful and the ministerial or hierarchical priesthood are none the less ordered one to another; each in its own proper way shares in the one priesthood of Christ.”
 Vatican Council II, Flannery, 427.
 Ibid. 428.
 “The distinction between clergy and laity will thus emerge with greater clarity, the distinction between what belongs to the clergy and is reserved to them and what can be entrusted to the laity. Their respective natures will thus be more clearly understood;” Ministeria Quaenam; ibid. 429.
 “To speak of the `participation of the lay faithful in the pastoral ministry of priests’ it is first of all necessary to reflect carefully on the term `ministry’ and on the various meanings it can have in theological and canonical language.
“For some time now it has been customary to use the word `ministries’ not only for the `officia’ and `munera’ exercised by pastors in virtue of the sacrament of orders, but also for those exercised by the lay faithful in virtue of the baptismal priesthood. The terminological question becomes even more complex and delicate when all the faithful are recognized as having the possibility of supplying – by official deputation given by pastors – certain functions more proper to clerics, which , nevertheless, do not require the character of orders (cf. Canon 230).
“It must be admitted that the language becomes doubtful, confused and hence not helpful for expressing the doctrine of the faith whenever the difference `of essence and not merely of degree’ between the baptismal priesthood and the ordained priesthood is in any way obscured (cf. `Lumen Gentium,’ 10).
“Similarly, by not making a clear distinction, including in pastoral practice, between the baptismal and hierarchical priesthood, one also runs the risk of underrating the theological `proprium’ of the laity and of forgetting `the specific ontological bond which unites the priesthood to Christ the high priest and good shepherd’ ((Pastores Dabo Vobis, 11
“A great variety of consequences follows from these reflections and should find expression in the revision of the motu proprio Ministeria Quaenam, as explicitly requested by the fathers attending the 1987 synod (Christifideles Laici, 23). Thus in the way it was prepared and carried out, the symposium held over the past few days has been most useful…” (bold mine); John Paul II, Address on the Participation of the Laity in the Priestly Ministry: Given in Rome by His Holiness on 22 April 1994 to the participants of the symposium.
 Some Questions Regarding Collaboration of Nonordained Faithful in Priests’ Sacred Ministry, August 15, 1997; Signed by Congregation for the Clergy; Pontifical Council for the Laity; Congregation for the Doctrine of the Faith; Congregation for Divine Worship and the Discipline of the Sacraments; Congregation for Bishops; Congregation for the Evangelization of Peoples; Congregation for Institutes of Consecrated Life and Societies of Apostolic Life; Pontifical Council for the Interpretation of Legislative Texts. The strongest statement of this unusually authoritative document is a reiteration of the central quote given above in footnote 4 in its own Article I, sections 1) and 2).
However, The document came from the Vatican with an addendum: “The Instruction: An Explanatory Note;” This “explanatory note” said: “3. This document is meant to encourage priests, to encourage vocations and to help the laity – (…) understand how our fundamental equality is compatible with an essential difference… 5. It is good to explain how such abuses have arisen: Our modern frame of mind leads us to understand far more easily the concept of function, and far less easily to understand what is meant by ontological configuration. It is easier to understand that there is a task related to the word, and less easy to understand that there are sacramental actions. We are very sensitive to the demands of functionality and good organization, and might be inclined generously in entrust to others among the faithful anything which does not directly require the ad validitatem powers of the priesthood….
Viewing things otherwise risks interpreting service in the Church as the exercise of power. We are conditioned by the individualist culture we inherited from the 16th century to think in terms of competition, power, efficiency, which means that we are in danger of setting ourselves up against one another instead of understanding that the very same services, when exercised by sacred ministers or by the faithful do not simply have the same meaning, because of the sacramental nature of the Church…” (T)ruth demands that we admit that we are here confronted oby a revealed mystery that is not on the same level as our categories and that the way we use reason must preserve its nature as mystery, and not replace it with our church structures.
6. It is because what is concerned here is a matter of meaning that such treat attention must be paid to the vocabulary that is used, as has begun to be realized in several countries. The terms pastor and minister cannot be used for everything.
7. … May this document lead the laity to become fully aware of what is specific to them and prepare them for the task that is truly theirs in the world and in the Church, rather than encourage them to view as a promotion the fact that they fulfill other tasks that they exercise as substitutes.”
 “The priest… in virtue of his configuration to Christ, the head and shepherd, the priest stands in this spousal relationship with regard to the community. Inasmuch as he represents Christ, the head, shepherd and spouse of the Church, the priest is placed not only in the Church but also in the forefront of the Church….’ It is not just what we do [ministerial functions], but our gift of self, which manifests Christ’s love for his flock… The gift of self, which is the source and synthesis of pastoral charity, is directed toward the Church… (This) distinguishes the exercise of the priestly ministry as an amoris officium… The gift of self has no limits…” Pastores Dabo Vobis, 23-23. Besides the power to teach, absolve and celebrate Mass, the layman is not empowered to die for the Church in this way as spouse.
 “This Marian profile is also – even perhaps more so – fundamental and characteristic for the Church as it the apostolic and Petrine profile to which it s profoundly united…. The Marian dimension of the Church is antecedent to that of the Petrine, without being in any way divided from it or being less complementary. Mary Immaculate precedes all others, including obviously Peter himself and the Apostles. This is so, not only because Peter and the Apostles, being born of the human race under the burden of sin, form part of the Church which is `holy from out of sinners,’ but also because their triple function has no other purpose except to form the Church in line with ideal of sanctity already programmed and prefigured in Mary. A contemporary theologian has rightly stated that Mary is `Queen of the Apostles without any pretensions to apostolic powers: she has other and greater powers’ (H. U. von Balthasar, Neue Klarstellungen).’" Address to the Cardinal and Prelates of the Roman Curia (December 22, 1987); L’Osservatore Romano, December 23, 1987; footnote 55 of John Paul II’s Mulieris Dignitatem.
 “Co-Workers In the Vineyard of the Lord” calls for vocation, selection, formation, public ceremony for conferring “office” and the replacement of the secular workplace by the “ministerial workplace.” This elite, the “lay ecclesial minister” is seeking a structure within the bishops’ conference and congruent powers. It indeed becomes a parallel structure to the ministerial priesthood.