earnings vs regular payment

earnings and regular payment both are nouns.

Word	Noun	Adjective	Verb	Adverb
earnings	Yes	No	No	No
regular payment	Yes	No	No	No

As nouns, regular payment is a hypernym of earnings; that is, regular payment is a word with a broader meaning than earnings:

earnings (noun)	regular payment (noun)
something that remunerates	a payment made at regular times
the excess of revenues over outlays in a given period of time (including depreciation and other non-cash expenses)