Mona vs Anglesey Island

Mona and Anglesey Island both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mona	Yes	No	No	No
Anglesey Island	Yes	No	No	No

As nouns, Mona and Anglesey Island are synonyms defined as:

Other synonyms of Mona include Anglesea, Anglesea Island, Anglesey.

Mona (noun)	Anglesey Island (noun)
an island to the northwest of Wales	an island to the northwest of Wales