child vs descendent

child and descendent both are nouns.

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

As nouns, descendent is a hypernym of child; that is, descendent is a word with a broader meaning than child:

Other hypernyms of child include descendant.

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

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