payment rate vs repayment rate

payment rate and repayment rate both are nouns.

Word	Noun	Adjective	Verb	Adverb
payment rate	Yes	No	No	No
repayment rate	Yes	No	No	No

As nouns, payment rate and repayment rate are synonyms defined as:

payment rate and repayment rate: the amount of money paid out per unit time

Other synonyms of payment rate include installment rate, rate of payment.

payment rate (noun)	repayment rate (noun)
the amount of money paid out per unit time	the amount of money paid out per unit time