It is thus the ministry of reconciliation, or to use another term, of priesthood, that is in view here. I personally would broaden that to include all of the spiritual gifts needed for ministry. The Holy Spirit was given fully to the apostles as the bearers of sacramental grace. What is not being fully manifest before Pentecost are some of the gifts and ministries empowered by the Spirit. Yet each of us receives different gifts, according to the will and gift of God.
Spiritual gifts are for ministry, and they are given accordingly.
In Acts 2, we see a broader reception of the power of the Holy Spirit. The apostles have already received their commission and are conscious of it. The gift of the Spirit was given to all, and the body of Christ, the Church, was formed. I do not believe that redactionary factors explain the differences in the passages. I believe they are complementary and reveal different aspects of the nature of the giving of the Holy Spirit's gifts for ministry.