all right vs okay

all right is not a noun while okay is a noun.

Word	Noun	Adjective	Verb	Adverb
all right	No	Yes	No	Yes
okay	Yes	Yes	Yes	Yes

As adjectives, all right and okay are synonyms defined as:

Other synonyms of all right include cool, fine, hunky-dory, o.k., ok.

As adverbs, all right and okay are synonyms defined as:

Other synonyms of all right include alright, O.K..

all right (noun)	okay (noun)
	an endorsement

all right (adjective)	okay (adjective)
being satisfactory or in satisfactory condition	being satisfactory or in satisfactory condition

all right (verb)	okay (verb)
	give sanction to

all right (adverb)	okay (adverb)
an expression of agreement normally occurring at the beginning of a sentence	in a satisfactory or adequate manner
without doubt (used to reinforce an assertion)
in a satisfactory or adequate manner