sweetie vs baby

sweetie and baby both are nouns.

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

As nouns, sweetie and baby are synonyms defined as:

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

sweetie (noun)	baby (noun)
a person loved by another person	a project of personal concern to someone
a beloved person; used as terms of endearment	a very young mammal
	a very young child (birth to 1 year) who has not yet begun to walk or talk
	the youngest member of a group (not necessarily young)
	an immature childish person
	an unborn child; a human fetus
	a beloved person; used as terms of endearment

sweetie (verb)	baby (verb)
	treat with excessive indulgence