The difference between Friar and Sister

Friar as a noun:

A member of a mendicant Christian order such as the Augustinians, Carmelites (white friars), Franciscans (grey friars) or the Dominicans (black friars).

Friar as a noun (printing, dated):

A white or pale patch on a printed page.

Friar as a noun:

An American fish, the silverside.

Sister as a noun:

A daughter of the same parents as another person; a female sibling.

Sister as a noun (informally):

A female member of a religious order; especially one devoted to more active service; a nun.

Sister as a noun:

Any butterfly in the genus , so named for the resemblance of the dark-colored wings to the black habit traditionally worn by nuns.

Sister as a noun (British):

A senior or supervisory nurse, often in a hospital.

Sister as a noun:

Any woman or girl with whom a bond is felt through common membership of a race, profession, religion or organization, such as feminism.

Sister as a noun (slang):

A black woman.

Sister as a noun (informal):

Sister as a noun:

A woman, in certain labour or socialist circles; also as a form of address.

Sister as a noun (attributively):

An entity that has a special or affectionate, non-hierarchical relationship with another.

Sister as a noun (comptheory):

A node in a data structure that shares its parent with another node.

Sister as a noun (usually, attributively):

Something in the same class.

Sister as a verb (transitive, construction):

To strengthen (a supporting beam) by fastening a second beam alongside it.

Sister as a verb (obsolete, transitive):

To be sister to; to resemble closely.