blue baby vs babe

blue baby and babe both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue baby	Yes	No	No	No
babe	Yes	No	No	No

As nouns, babe is a hypernym of blue baby; that is, babe is a word with a broader meaning than blue baby:

blue baby: an infant born with a bluish color; usually has a defective heart
babe: a very young child (birth to 1 year) who has not yet begun to walk or talk

Other hypernyms of blue baby include baby, infant.

blue baby (noun)	babe (noun)
an infant born with a bluish color; usually has a defective heart	a very young child (birth to 1 year) who has not yet begun to walk or talk