pay envelope vs salary

pay envelope and salary both are nouns.

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

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

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

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

pay envelope (noun)	salary (noun)
wages enclosed in an envelope for distribution to the wage earner	something that remunerates