payment vs down payment

payment and down payment both are nouns.

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

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

payment: a sum of money paid or a claim discharged
down payment: a partial payment made at the time of purchase; the balance to be paid later

payment (noun)	down payment (noun)
the act of paying money	a partial payment made at the time of purchase; the balance to be paid later
an act of requiting; returning in kind
a sum of money paid or a claim discharged