offspring vs child

offspring and child both are nouns.

Word	Noun	Adjective	Verb	Adverb
offspring	Yes	No	No	No
child	Yes	No	No	No

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

offspring (noun)	child (noun)
any immature animal	a young person of either sex
something that comes into existence as a result	a human offspring (son or daughter) of any age
the immediate descendants of a person	an immature childish person
	a member of a clan or tribe