love child vs by-blow

love child and by-blow both are nouns.

Word	Noun	Adjective	Verb	Adverb
love child	Yes	No	No	No
by-blow	Yes	No	No	No

As nouns, love child and by-blow are synonyms defined as:

Other synonyms of love child include bastard, illegitimate, illegitimate child, whoreson.

love child (noun)	by-blow (noun)
the illegitimate offspring of unmarried parents	the illegitimate offspring of unmarried parents