penniless vs in straitened circumstances

penniless and in straitened circumstances both are adjectives.

Word	Noun	Adjective	Verb	Adverb
penniless	No	Yes	No	No
in straitened circumstances	No	Yes	No	No

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

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

Other synonyms of penniless include hard up, impecunious, penurious, pinched.

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