Anglesey Island vs Mona

Anglesey Island and Mona both are nouns.

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

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

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

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