Mt. McKinley vs Mount McKinley

Mt. McKinley and Mount McKinley both are nouns.

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

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

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

Other synonyms of Mt. McKinley include Denali, McKinley.

Mt. McKinley (noun)	Mount 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)