immediate payment vs cash

immediate payment and cash both are nouns.

Word	Noun	Adjective	Verb	Adverb
immediate payment	Yes	No	No	No
cash	Yes	No	Yes	No

As nouns, immediate payment and cash are synonyms defined as:

immediate payment and cash: prompt payment for goods or services in currency or by check

immediate payment (noun)	cash (noun)
prompt payment for goods or services in currency or by check	money in the form of bills or coins
	prompt payment for goods or services in currency or by check

immediate payment (verb)	cash (verb)
	exchange for cash