Third World vs accumulation

Third World and accumulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
Third World	Yes	No	No	No
accumulation	Yes	No	No	No

As nouns, accumulation is a hypernym of Third World; that is, accumulation is a word with a broader meaning than Third World:

Third World: underdeveloped and developing countries of Asia and Africa and Latin America collectively
accumulation: several things grouped together or considered as a whole

Other hypernyms of Third World include aggregation, assemblage, collection.

Third World (noun)	accumulation (noun)
underdeveloped and developing countries of Asia and Africa and Latin America collectively	the act of accumulating
	several things grouped together or considered as a whole
	(finance) profits that are not paid out as dividends but are added to the capital base of the corporation
	an increase by natural growth or addition