in straitened circumstances vs hard up

in straitened circumstances and hard up both are adjectives.

Word	Noun	Adjective	Verb	Adverb
in straitened circumstances	No	Yes	No	No
hard up	No	Yes	No	No

As adjectives, in straitened circumstances and hard up are synonyms defined as:

in straitened circumstances and hard up: not having enough money to pay for necessities

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

in straitened circumstances (adjective)	hard up (adjective)
not having enough money to pay for necessities	not having enough money to pay for necessities