straight shooter vs straight arrow

straight shooter and straight arrow both are nouns.

Word	Noun	Adjective	Verb	Adverb
straight shooter	Yes	No	No	No
straight arrow	Yes	No	No	No

As nouns, straight shooter and straight arrow are synonyms defined as:

Other synonyms of straight shooter include square shooter.

straight shooter (noun)	straight arrow (noun)
a frank and honest person	a frank and honest person