adjective vs major form class

adjective and major form class both are nouns.

Word	Noun	Adjective	Verb	Adverb
adjective	Yes	Yes	No	No
major form class	Yes	No	No	No

As nouns, major form class is a hypernym of adjective; that is, major form class is a word with a broader meaning than adjective:

adjective (noun)	major form class (noun)
a word that expresses an attribute of something	any of the major parts of speech of traditional grammar
the word class that qualifies nouns

adjective (adjective)	major form class (adjective)
relating to court practice and procedure as opposed to the principles of law
of or relating to or functioning as an adjective