Mt. St. Helens vs Mount Saint Helens

Mt. St. Helens and Mount Saint Helens both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mt. St. Helens	Yes	No	No	No
Mount Saint Helens	Yes	No	No	No

As nouns, Mt. St. Helens and Mount Saint Helens are synonyms defined as:

Mt. St. Helens and Mount Saint Helens: an active volcano in the Cascade Range in southwestern Washington; erupted violently in 1980 after 123 years of inactivity

Other synonyms of Mt. St. Helens include Mount St. Helens.

Mt. St. Helens (noun)	Mount Saint Helens (noun)
an active volcano in the Cascade Range in southwestern Washington; erupted violently in 1980 after 123 years of inactivity	an active volcano in the Cascade Range in southwestern Washington; erupted violently in 1980 after 123 years of inactivity