family tree vs descent

family tree and descent both are nouns.

Word	Noun	Adjective	Verb	Adverb
family tree	Yes	No	No	No
descent	Yes	No	No	No

As nouns, descent is a hyponym of family tree; that is, descent is a word with a more specific, narrower meaning than family tree:

family tree (noun)	descent (noun)
successive generations of kin	the act of changing your location in a downward direction
	properties attributable to your ancestry
	a movement downward
	the hereditary derivation of an individual
	a downward slope or bend
	the kinship relation between an individual and the individual's progenitors