pay envelope vs earnings

pay envelope and earnings both are nouns.

Word	Noun	Adjective	Verb	Adverb
pay envelope	Yes	No	No	No
earnings	Yes	No	No	No

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

pay envelope: wages enclosed in an envelope for distribution to the wage earner
earnings: something that remunerates

Other hypernyms of pay envelope include pay, remuneration, salary, wage.

pay envelope (noun)	earnings (noun)
wages enclosed in an envelope for distribution to the wage earner	something that remunerates
	the excess of revenues over outlays in a given period of time (including depreciation and other non-cash expenses)