Sissy vs. Sister: What's the Difference?

Sissy

Sissy is a pejorative term, especially in the U.S., for an effeminate boy or man, with connotations of being homosexual or cowardly.
Sister

A sister is the female sibling. Although the term typically refers to the consanguineal relationship, it is sometimes used endearingly to refer to non-consanguineal relationships.

Wikipedia

Sister (noun)

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

“My sister is always driving me crazy.”
Sister (noun)

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

“Michelle left behind her bank job and became a sister at the local convent.”
Sister (noun)

Any butterfly in the genus noshow=1, so named for the resemblance of the dark-colored wings to the black habit traditionally worn by nuns.
Sister (noun)

A senior or supervisory nurse, often in a hospital.
Sister (noun)

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

“Connie was very close to her friend Judy and considered her to be her sister.”
Sister (noun)

A black woman.
Sister (noun)

A form of address to a woman.
Sister (noun)

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

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

“sister publication, sister city, sister projects”
Sister (noun)

A node in a data structure that shares its parent with another node.
Sister (noun)

Something in the same class.

“sister ships, sister facility”
Sister (verb)

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

“I’m trying to correct my sagging floor by sistering the joists.”
Sister (verb)

To be sister to; to resemble closely.

Wiktionary

Sissy vs. Sister