dude vs fellow

dude and fellow both are nouns.

Word	Noun	Adjective	Verb	Adverb
dude	Yes	No	No	No
fellow	Yes	No	No	No

As nouns, dude and fellow are synonyms defined as:

Other synonyms of dude include buster.

dude (noun)	fellow (noun)
a man who is much concerned with his dress and appearance	a boy or man
an informal form of address for a man	a man who is the lover of a man or woman
	a friend who is frequently in the company of another
	a person who is member of one's class or profession
	an informal form of address for a man
	a member of a learned society
	one of a pair