Altai Mountains vs Altay Mountains

Altai Mountains and Altay Mountains both are nouns.

Word	Noun	Adjective	Verb	Adverb
Altai Mountains	Yes	No	No	No
Altay Mountains	Yes	No	No	No

As nouns, Altai Mountains and Altay Mountains are synonyms defined as:

Altai Mountains and Altay Mountains: a mountain range in central Asia that extends a thousand miles from Kazakhstan eastward into western Mongolia and northern China

Altai Mountains (noun)	Altay Mountains (noun)
a mountain range in central Asia that extends a thousand miles from Kazakhstan eastward into western Mongolia and northern China	a mountain range in central Asia that extends a thousand miles from Kazakhstan eastward into western Mongolia and northern China