suffering vs unhappy

suffering is a noun but unhappy is not a noun.

Word	Noun	Adjective	Verb	Adverb
suffering	Yes	Yes	No	No
unhappy	No	Yes	No	No

suffering (noun)	unhappy (noun)
feelings of mental or physical pain
psychological suffering
a state of acute pain
misery resulting from affliction

suffering (adjective)	unhappy (adjective)
troubled by pain or loss	experiencing or marked by or causing sadness or sorrow or discontent
very unhappy; full of misery	generalized feeling of distress
	marked by or producing unhappiness
	causing discomfort