baby vs war baby

baby and war baby both are nouns.

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

As nouns, war baby is a hyponym of baby; that is, war baby is a word with a more specific, narrower meaning than baby:

baby: a very young child (birth to 1 year) who has not yet begun to walk or talk
war baby: conceived or born during war

baby (noun)	war baby (noun)
a project of personal concern to someone	conceived or born during war
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

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