RPA-ABB vs terrorist organization

RPA-ABB and terrorist organization both are nouns.

Word	Noun	Adjective	Verb	Adverb
RPA-ABB	Yes	No	No	No
terrorist organization	Yes	No	No	No

RPA-ABB (noun)	terrorist organization (noun)
an urban hit squad and guerrilla group of the Communist Party in the Philippines; formed in the 1980s	a political movement that uses terror as a weapon to achieve its goals