Mount Etna vs Mt Etna

Mount Etna and Mt Etna both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mount Etna	Yes	No	No	No
Mt Etna	Yes	No	No	No

As nouns, Mount Etna and Mt Etna are synonyms defined as:

Mount Etna and Mt Etna: an inactive volcano in Sicily; last erupted in 1961; the highest volcano in Europe (10,500 feet)

Other synonyms of Mount Etna include Etna.

Mount Etna (noun)	Mt Etna (noun)
an inactive volcano in Sicily; last erupted in 1961; the highest volcano in Europe (10,500 feet)	an inactive volcano in Sicily; last erupted in 1961; the highest volcano in Europe (10,500 feet)