ease up vs decrease

ease up is not a noun while decrease is a noun.

Word	Noun	Adjective	Verb	Adverb
ease up	No	No	Yes	No
decrease	Yes	No	Yes	No

As verbs, decrease is a hypernym of ease up; that is, decrease is a word with a broader meaning than ease up:

Other hypernyms of ease up include diminish, fall, lessen.

ease up (noun)	decrease (noun)
	the act of decreasing or reducing something
	the amount by which something decreases
	a change downward
	a process of becoming smaller or shorter

ease up (verb)	decrease (verb)
become less intense	decrease in size, extent, or range
reduce pressure or intensity	make become smaller
move in order to make room for someone for something