Mordva vs Mordvin

Mordva and Mordvin both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mordva	Yes	No	No	No
Mordvin	Yes	No	No	No

As nouns, Mordva and Mordvin are synonyms defined as:

Other synonyms of Mordva include Mordva language, Mordvin language, Mordvinian, Mordvinian language.

As nouns, Mordva and Mordvin are synonyms defined as:

Mordva and Mordvin: a member of the agricultural people living in the central Volga provinces of European Russia

Other synonyms of Mordva include Mordvinian.

Mordva (noun)	Mordvin (noun)
the Finnic language spoken by the Mordvinians	the Finnic language spoken by the Mordvinians
a member of the agricultural people living in the central Volga provinces of European Russia	a member of the agricultural people living in the central Volga provinces of European Russia