tall vs difficult

tall is a noun but difficult is not a noun.

Word	Noun	Adjective	Verb	Adverb
tall	Yes	Yes	No	No
difficult	No	Yes	No	No

tall (noun)	difficult (noun)
a garment size for a tall person

tall (adjective)	difficult (adjective)
great in vertical dimension; high in stature	not easy; requiring great physical or mental effort to accomplish or comprehend or endure
impressively difficult	hard to control
too improbable to admit of belief
lofty in style
having a specified height