treetop vs capitulum

treetop and capitulum both are nouns.

Word	Noun	Adjective	Verb	Adverb
treetop	Yes	No	No	No
capitulum	Yes	No	No	No

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

treetop: the upper branches and leaves of a tree or other plant
capitulum: an arrangement of leafy branches forming the top or head of a tree

treetop (noun)	capitulum (noun)
the upper branches and leaves of a tree or other plant	a dense cluster of flowers or foliage
	fruiting spike of a cereal plant especially corn
	an arrangement of leafy branches forming the top or head of a tree