is that clergy is body of persons, such as ministers, sheiks, priests and rabbis, who are trained and ordained for religious service while monks is plural of lang=en.
is that nun is a member of a Christian religious community of women who live by certain vows and usually wear a habit, in some cases living together in a cloister while monks is plural of lang=en.
is that friar is a member of a mendicant christian order such as the augustinians, carmelites (white friars), franciscans (grey friars) or the dominicans (black friars) while monks is .