separate vs reduce

separate is a noun but reduce is not a noun.

Word	Noun	Adjective	Verb	Adverb
separate	Yes	Yes	Yes	No
reduce	No	No	Yes	No

As verbs, reduce is a hyponym of separate; that is, reduce is a word with a more specific, narrower meaning than separate:

separate (noun)	reduce (noun)
a garment that can be purchased separately and worn in combinations with other garments
a separately printed article that originally appeared in a larger publication

separate (adjective)	reduce (adjective)
independent; not united or joint
standing apart; not attached to or supported by anything
separated according to race, sex, class, or religion
have the connection undone; having become separate

separate (verb)	reduce (verb)
become separated into pieces or fragments	take off weight
divide into two or more branches so as to form a fork	cut down on; make a reduction in
arrange or order by classes or categories	narrow or limit
mark as different	cook until very little liquid is left
move or break apart	to remove oxygen from a compound, or cause to react with hydrogen or form a hydride, or to undergo an increase in the number of electrons
force, take, or pull apart	make smaller
divide into components or constituents	reduce in size; reduce physically
go one's own way; move apart	make less complex
make a division or separation	reduce in scope while retaining essential elements
treat differently on the basis of sex or race	lessen the strength or flavor of a solution or mixture
separate into parts or portions	be cooked until very little liquid is left
discontinue an association or relation; go different ways	be the essential element
act as a barrier between; stand between	destress and thus weaken a sound when pronouncing it
	undergo meiosis
	reposition (a broken bone after surgery) back to its normal site
	lower in grade or rank or force somebody into an undignified situation
	lessen and make more modest
	simplify the form of a mathematical equation of expression by substituting one term for another
	bring to humbler or weaker state or condition
	put down by force or intimidation