unrestricted vs grammar

unrestricted is not a noun while grammar is a noun.

Word	Noun	Adjective	Verb	Adverb
unrestricted	No	Yes	No	No
grammar	Yes	No	No	No

unrestricted (noun)	grammar (noun)
	the branch of linguistics that deals with syntax and morphology (and sometimes also deals with semantics)

unrestricted (adjective)	grammar (adjective)
not subject to or subjected to restriction
free of restrictions on conduct
not restricted or exclusive
never having had security classification
not restricted or modified in meaning