straight arrow vs straight shooter

straight arrow and straight shooter both are nouns.

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

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

Other synonyms of straight arrow include square shooter.

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