kolkhoznik vs fellow member

kolkhoznik and fellow member both are nouns.

Word	Noun	Adjective	Verb	Adverb
kolkhoznik	Yes	No	No	No
fellow member	Yes	No	No	No

As nouns, fellow member is a hypernym of kolkhoznik; that is, fellow member is a word with a broader meaning than kolkhoznik:

kolkhoznik: a member of a kolkhoz
fellow member: one of the persons who compose a social group (especially individuals who have joined and participate in a group organization)

Other hypernyms of kolkhoznik include member.

kolkhoznik (noun)	fellow member (noun)
a member of a kolkhoz	one of the persons who compose a social group (especially individuals who have joined and participate in a group organization)