descendent vs child

descendent and child both are nouns.

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

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

Other hyponyms of descendent include scion.

descendent (noun)	child (noun)
a person considered as descended from some ancestor	a young person of either sex
	a human offspring (son or daughter) of any age
	an immature childish person
	a member of a clan or tribe

descendent (adjective)	child (adjective)
going or coming down
proceeding by descent from an ancestor