A missionary order is a Catholic religious order devoted to active missionary work. No Catholic religious order was founded for that purpose, but all the mendicant orders have been active in this field and others too, in particular the Jesuits, whose members include outstanding missionaries such as Saint Francis Xavier and Matteo Ricci. Even monastic orders have engaged and still engage in missionary endeavours, as did, for instance, the Benedictines whom Pope Gregory the Great sent to evangelize the Angles.
A missionary congregation is a religious congregation devoted to active missionary work. Some, as that of the Marist Fathers, have that field of work as the purpose for which they were founded. It has also been suggested that all congregations, at their foundation, are missionary focussed. The largest Catholic missionary congregation is the Society of the Divine Word.