Associations of the faithful are different from Institutes of Consecrated Life and Societies of Apostolic Life.
According to the Law of the Catholic Church, an Association of the faithful (called "pious union" before 1983, under the Code of Canon Law of 1917) is a group of Catholics (Lay People or Clerics, or Clerics and Laity together) who work together to promote a more perfect life, promote public worship or Christian doctrine, or exercise an apostolate (e.g. evangelization, works of piety or charity) and coordinate the temporal order in a Christian spirit.
They are established by the competent authority of the Church, i.e. the Bishop (Diocesan Associations), Conference of Bishops (National Associations) or the Holy See (International Associations).
Depending on the goals pursued, an association of the faithful can be established as a public or private legal entity. They could be Public or Private Associations.
Private associations, such as the WORK of the Foyer de Charité are run by the Faithful in accordance with the provisions of their Statutes. As a result, they benefit from a certain independence. Associations of the Faithful are governed by their own Canonical Statutes, which can be expanded on in their Customary Rules or Internal Regulations.