Q. 1. Is there a difference between a religious nun versus a religious sister?
A. 1. While the term nun and sister are often interchanged, in some cases they have a different meaning. A nun is a religious female who lives a contemplative cloistered life of prayer and meditation, while a sister, in Christian denominations, lives an active vocation of prayer and service, often to the needy, sick, poor, and uneducated.
A nun usually leaves mainstream society in order to live a life of prayer and contemplation in a monastery, a cloister or a convent.
The religious community of a nun is referred to as a "religious order" while the religious community of a sister is referred to as an "institute" or "congregation". All nuns are religious sisters, but not all religious sisters are, properly speaking, nuns.
Nuns and sisters are distinguished by the type of vows they take (solemn vows versus simple vows) and the focus of their good works.
Nuns are restricted from leaving the cloister. In essence, the work of a nun is within the confines of her monastery, while the work of a sister is in the greater world.
Both sisters and nuns are addressed as "Sister".