Oceanica vs Oceania

Oceanica and Oceania both are nouns.

Word	Noun	Adjective	Verb	Adverb
Oceanica	Yes	No	No	No
Oceania	Yes	No	No	No

As nouns, Oceanica and Oceania are synonyms defined as:

Oceanica and Oceania: a large group of islands in the south Pacific including Melanesia and Micronesia and Polynesia (and sometimes Australasia and the Malay Archipelago)

Oceanica (noun)	Oceania (noun)
a large group of islands in the south Pacific including Melanesia and Micronesia and Polynesia (and sometimes Australasia and the Malay Archipelago)	a large group of islands in the south Pacific including Melanesia and Micronesia and Polynesia (and sometimes Australasia and the Malay Archipelago)