payment vs outlay

payment and outlay both are nouns.

Word	Noun	Adjective	Verb	Adverb
payment	Yes	No	No	No
outlay	Yes	No	No	No

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

payment (noun)	outlay (noun)
the act of paying money	the act of spending or disbursing money
an act of requiting; returning in kind	money paid out; an amount spent
a sum of money paid or a claim discharged