darling vs sweetie

darling and sweetie both are nouns.

Word	Noun	Adjective	Verb	Adverb
darling	Yes	Yes	No	No
sweetie	Yes	No	No	No

As nouns, darling and sweetie are synonyms defined as:

Other synonyms of darling include baby, beloved, dear, dearest, dearie, deary, honey, love, sweetheart.

darling (noun)	sweetie (noun)
a special loved one	a person loved by another person
a beloved person; used as terms of endearment	a beloved person; used as terms of endearment

darling (adjective)	sweetie (adjective)
dearly loved