Mongol vs Mongol Tatar

Mongol and Mongol Tatar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mongol	Yes	Yes	No	No
Mongol Tatar	Yes	No	No	No

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

Mongol: a member of the nomadic peoples of Mongolia
Mongol Tatar: a member of the Mongolian people of central Asia who invaded Russia in the 13th century

Other hyponyms of Mongol include Tartar, Tatar, Kalka, Khalka, Khalkha.

Mongol (noun)	Mongol Tatar (noun)
a member of the nomadic peoples of Mongolia	a member of the Mongolian people of central Asia who invaded Russia in the 13th century

Mongol (adjective)	Mongol Tatar (adjective)
of or relating to the region of Mongolia or its people or their languages or cultures