summit vs hilltop

summit and hilltop both are nouns.

Word	Noun	Adjective	Verb	Adverb
summit	Yes	No	Yes	No
hilltop	Yes	No	No	No

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

Other hyponyms of summit include brow, pinnacle, mountain peak.

summit (noun)	hilltop (noun)
a meeting of heads of governments	the peak of a hill
the top or extreme point of something (usually a mountain or hill)
the highest level or degree attainable; the highest stage of development

summit (verb)	hilltop (verb)
reach the summit (of a mountain)