Russian vs Chechen

Russian and Chechen both are nouns.

Word	Noun	Adjective	Verb	Adverb
Russian	Yes	Yes	No	No
Chechen	Yes	Yes	No	No

As nouns, Chechen is a hyponym of Russian; that is, Chechen is a word with a more specific, narrower meaning than Russian:

Russian (noun)	Chechen (noun)
the Slavic language that is the official language of Russia	a northern Caucasian language spoken by the Chechen
a native or inhabitant of Russia	a native or inhabitant of Chechnya

Russian (adjective)	Chechen (adjective)
of or pertaining to or characteristic of Russia or its people or culture or language	of or relating to Chechnya or its people or culture