lower vs decrease

lower and decrease both are nouns.

Word	Noun	Adjective	Verb	Adverb
lower	Yes	Yes	Yes	No
decrease	Yes	No	Yes	No

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

Other hypernyms of lower include lessen, minify.

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

lower (adjective)	decrease (adjective)
the bottom one of two

lower (verb)	decrease (verb)
make lower or quieter	decrease in size, extent, or range
set lower	make become smaller
cause to drop or sink
move something or somebody to a lower position
look angry or sullen, wrinkle one's forehead, as if to signal disapproval