brother vs comrade

brother and comrade both are nouns.

Word	Noun	Adjective	Verb	Adverb
brother	Yes	No	No	No
comrade	Yes	No	No	No

As nouns, brother and comrade are synonyms defined as:

brother and comrade: used as a term of address for those male persons engaged in the same movement

brother (noun)	comrade (noun)
a male with the same parents as someone else	a friend who is frequently in the company of another
a male person who is a fellow member (of a fraternity or religion or other group)	used as a term of address for those male persons engaged in the same movement
a close friend who accompanies his buddies in their activities
used as a term of address for those male persons engaged in the same movement