Religious orders were groups of clergy bound by certain rules. Member who lived apart from society, like the Nun and the Monk, were of the monastic order and members who lived in society, like the Friar, were of the secular order. Those who were expected to live as beggars and depend on charity to live were of the mendicant order.
The Monk is a member of the monastic order. He believes the rules that govern monks are outdated and he chooses not to obey them. He owns horses and greyhounds and spends much of his time hunting. Owning pets and hunting are just two of the rules the Monk breaks. He owns fine clothes and wears a pin in the shape of a lover's knot. He indulges in worldly possessions and also in food. He is fat and his favorite food is a whole roasted swan. The Monk should be living a life of poverty yet he clearly is not.
The Friar is a member of the mendicant order. He is a limiter and is supposed to minister to people in his area. The Friar mainly associates with wealthy people who can better support him. He is a regular in bars and taverns and he won't associate with lepers. The Friar is motivated by greed. He hears confessions for a fee although he is not qualified to do so.
The Parson is a member of the secular order. He lives in society and is not bound by the monastic rules that govern the Nun and the Monk. The Parson is poor and pious. He leads by example and is truly concerned about the salvation of his parishioners. His goal is to get them into heaven. Although he does not make enough money to meet his own needs, he still shares what he has with those who need it.