fellow vs dude

fellow and dude both are nouns.

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

As nouns, fellow and dude are synonyms defined as:

Other synonyms of fellow include buster.

fellow (noun)	dude (noun)
a boy or man	a man who is much concerned with his dress and appearance
a man who is the lover of a man or woman	an informal form of address for a man
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