Peninsular Malaysia vs West Malaysia

Peninsular Malaysia and West Malaysia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Peninsular Malaysia	Yes	No	No	No
West Malaysia	Yes	No	No	No

As nouns, Peninsular Malaysia and West Malaysia are synonyms defined as:

Peninsular Malaysia and West Malaysia: the region of Malaysia on the Malay Peninsula; shares a land border with Thailand to the north

Other synonyms of Peninsular Malaysia include Malaya.

Peninsular Malaysia (noun)	West Malaysia (noun)
the region of Malaysia on the Malay Peninsula; shares a land border with Thailand to the north	the region of Malaysia on the Malay Peninsula; shares a land border with Thailand to the north