illegitimate child vs love child

illegitimate child and love child both are nouns.

Word	Noun	Adjective	Verb	Adverb
illegitimate child	Yes	No	No	No
love child	Yes	No	No	No

As nouns, illegitimate child and love child are synonyms defined as:

illegitimate child and love child: the illegitimate offspring of unmarried parents

Other synonyms of illegitimate child include bastard, by-blow, illegitimate, whoreson.

illegitimate child (noun)	love child (noun)
the illegitimate offspring of unmarried parents	the illegitimate offspring of unmarried parents