rampart vs crenellation

rampart and crenellation both are nouns.

Word	Noun	Adjective	Verb	Adverb
rampart	Yes	No	No	No
crenellation	Yes	No	No	No

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

rampart: an embankment built around a space for defensive purposes
crenellation: a rampart built around the top of a castle with regular gaps for firing arrows or guns

Other hyponyms of rampart include bailey, battlement, crenelation, earthwork, fraise, merlon.

rampart (noun)	crenellation (noun)
an embankment built around a space for defensive purposes	the action of constructing ramparts with gaps for firing guns or arrows
	a rampart built around the top of a castle with regular gaps for firing arrows or guns