Mount McKinley vs Mt. McKinley

Mount McKinley and Mt. McKinley both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mount McKinley	Yes	No	No	No
Mt. McKinley	Yes	No	No	No

As nouns, Mount McKinley and Mt. McKinley are synonyms defined as:

Mount McKinley and Mt. McKinley: a mountain in south central Alaska; the highest peak in North America (20,300 feet high)

Other synonyms of Mount McKinley include Denali, McKinley.

Mount McKinley (noun)	Mt. McKinley (noun)
a mountain in south central Alaska; the highest peak in North America (20,300 feet high)	a mountain in south central Alaska; the highest peak in North America (20,300 feet high)