Thanks for your questions. I realize I haven't really explained why ecclesial vocations differ from those that are not considered ecclesial in the proper sense of the term, and also, I never really defined the term. So yes, thanks! Lumen Gentium said the following: [[(the profession of the evangelical counsels) indisputably belongs to the life and holiness of the church.]] and also, [[The evangelical counsels which lead to charity join their followers to the Church and its mystery in a special way.]] (#44) In Vita Consecrata, John Paul II enlarged on the first citation above, saying, [[This means that the consecrated life, present in the Church from the beginning, can never fail to be one of her essential and characteristic elements, for it expresses her very nature.]] (#29) When I speak of the vocation belonging to the Church herself before it belongs to the individual to whom it is entrusted, or that consecrated eremitical life is lived for the sake of the Church herself or (another way of saying this) that it is lived so the Church can truly be the Church she is called to be, yes, I am talking about these two points made by Luman Gentium and John Paul II, just as you also noted in your question.
Every vocation to the consecrated state recognizes they belong as an essential (foundational and necessary) part of the holiness and life of the Church. As JPII also wrote in the same section, "The idea of a Church made up only of sacred ministers and lay people does not, therefore, conform to the intentions of her divine Founder as revealed to us by the gospels and the other writings of the New Testament." (VC# 29) Moreover, this essential part of the Church's very constitution as the Body of Christ serves both sacred ministers and laity while technically belonging to neither group (it is drawn from both). It is an eschatological sign to both regarding what it means to be more fully conformed to Christ. It reminds members of both these hierarchical groups, that following Christ is not about power or the exercise of power, nor is it about slavish subservience, but instead, it is about close union with Christ that leads to the freedom to respond maturely as Church (ecclesiola) in service to every need in both Church and world.
You can imagine what distortions might well occur if the Church were only comprised of "sacred ministers and laity"!! Clericalism is a terrible and destructive form of this which fails both clergy and laity as it fails Christ and his Church. Vocations to consecrated life call both hierarchical groups to greater holiness and humility as servant disciples of Christ. This presence of consecrated persons in the Church serves as an immediate summons to clerics to truly be priests in the mode of Christ and to members of the laity to realize the fullness and great responsibility of their baptismal consecration.Thus too, God and the Church herself calls persons to the consecrated state. These persons enter this state through a second and special consecration that differs from baptismal consecration. John Paul II continues in Vita Consecrata, [[In the Church's tradition religious profession [now including the profession and consecration of c 603 hermits] is considered to be a special and fruitful deepening of the consecration received in Baptism, inasmuch as it is the means by which the close union with Christ already begun in Baptism develops in the gift of a fuller, more explicit and authentic configuration to him through the profession of the evangelical counsels. This further consecration, however, differs in a special way from baptismal consecration, of which it is not a necessary consequence.]]
John Paul II continues, [[In fact, all those reborn in Christ are called to live out, with the strength which is the Spirit's gift, the chastity appropriate to their state of life, obedience to God and to the Church, and a reasonable detachment from material possessions: for all are called to holiness, which consists in the perfection of love. But Baptism in itself does not include the call to celibacy or virginity, the renunciation of possessions or obedience to a superior, in the form proper to the evangelical counsels. The profession of the evangelical counsels thus presupposes a particular gift of God not given to everyone, as Jesus himself emphasizes with respect to voluntary celibacy (cf. Mt 19:10-12). This call is accompanied, moreover, by a specific gift of the Holy Spirit, so that consecrated persons can respond to their vocation and mission. For this reason, as the liturgies of the East and West testify in the rite of monastic or religious profession and in the consecration of virgins, the Church invokes the gift of the Holy Spirit upon those who have been chosen and joins their oblation to the sacrifice of Christ.]]
We can look at some more of what Vita Consecrata (and maybe Lumen Gentium) says about ecclesial vocations later, especially if these posts raise more questions, but for the purposes of this article, I want to emphasize the way vocations to the consecrated state "belong to [and serve] the Church" as Church in an essential and characteristic way. When I speak of ecclesial vocations then, I am speaking about vocations that belong to the Church and help constitute her as Church in a very direct and immediate way. God, through the Church's mediation calls these vocations forth, and entrusts the Church with their supervision and governance. (This means too that these vocations are established in law (canon law) and that those who are called to such vocations take on the appropriate rights and obligations (expressed in additional canon laws) of such vocations.) Above all, I think, vocations to the consecrated state of life are a source of hope to the whole Church that it will remain the Church Christ wills to represent him to the World.