Devon vs Devonshire

Devon and Devonshire both are nouns.

Word	Noun	Adjective	Verb	Adverb
Devon	Yes	No	No	No
Devonshire	Yes	No	No	No

As nouns, Devon and Devonshire are synonyms defined as:

Devon and Devonshire: a county in southwestern England, named for the Dumnonii, a Celtic tribe

Devon (noun)	Devonshire (noun)
red dual-purpose cattle of English origin	a county in southwestern England, named for the Dumnonii, a Celtic tribe
a county in southwestern England, named for the Dumnonii, a Celtic tribe