strait and narrow vs straight and narrow

strait and narrow and straight and narrow both are nouns.

Word	Noun	Adjective	Verb	Adverb
strait and narrow	Yes	No	No	No
straight and narrow	Yes	No	No	No

As nouns, strait and narrow and straight and narrow are synonyms defined as:

strait and narrow and straight and narrow: the way of proper and honest behavior

strait and narrow (noun)	straight and narrow (noun)
the way of proper and honest behavior	the way of proper and honest behavior