hard up vs impecunious

hard up and impecunious both are adjectives.

Word	Noun	Adjective	Verb	Adverb
hard up	No	Yes	No	No
impecunious	No	Yes	No	No

As adjectives, hard up and impecunious are synonyms defined as:

Other synonyms of hard up include in straitened circumstances, penniless, penurious, pinched.

hard up (adjective)	impecunious (adjective)
not having enough money to pay for necessities	not having enough money to pay for necessities