Pope Francis has just released an Apostolic Exhortation called Evangelii Gaudium (The Joy of the Gospel). He also released an Encyclical Letter in the summer called Lumen Fidei (The Light of Faith). What is the difference between these two types of documents? Is one considered to be more important than the other?
Apostolic Exhortation is a type of communication from the Pope that is written to encourage people to undertake an implementation of particular set of recommendations listed in the document.
Encyclical Letter which is usually more important than Apostolic Exhortation is a letter that usually deals with a specific doctrine, where the doctrine is clarified, or explained in greater detail.
On the cover of Evangelii Gaudium it has the further description "Apostolic Exhortation on the Proclamation of the Gospel in today's world". Inside on the publishing page it says an "Encyclical Letter of Pope Francis Evangelii Gaudium". An exhortation is what it is FOR. An encyclical is what it IS.
What is the difference between an Apostolic Exhortation and an Encyclical Letter?
Generally speaking encyclicals are more important than apostolic exhortations.
A papal document treating of matters related to the general welfare of the Church, sent by the Pope to the bishops. Used especially in modern times to express the mind of the Pope to the people. Although of themselves not infallible documents, encyclicals may (and generally do) contain pronouncements on faith and morals that are de facto infallible because they express the ordinary teaching of the Church. In any case, the faithful are to give the papal encyclicals their interior assent and external respect as statements of the Vicar of Christ.
An encyclical epistle is like an encyclical letter but addressed to part of the Church, that is, to the bishops and faithful of a particular area. Its contents may be doctrinal, moral, or disciplinary matters of universal significance, but may also commemorate some historical event or treat of conditions in a certain country or locality.
Apostolic exhortations are of lesser importance, written by the pope.
An apostolic exhortation is a magisterial document written by the pope. It is considered third in importance, after apostolic constitutions and encyclicals. Exhortations generally encourage a particular virtue or activity. Apostolic exhortations are frequently issued following a Synod of Bishops, in which case they are known as post-synodal apostolic exhortations. They do not define Church doctrine and are not considered legislative.
As for Apostolic Letters they are presently used for Papal briefs.
Generally speaking, all documents issued by the Holy See. Formerly papal bulls and briefs were apostolic letters. Since St. Pius X, only documents in brief form used for lesser appointments, erecting or dividing mission territory, designating basilicas, and approving religious congregations are so designated.