Is the caroni plain another name for nothern lowlands?

No, the Caroni Plain and the Northern Lowlands refer to different geographic areas in Trinidad. The Caroni Plain is a specific low-lying region characterized by its fertile soil and is located in the central part of Trinidad, primarily surrounding the Caroni River. The Northern Lowlands, on the other hand, encompass a broader area that includes various lowland regions in the northern part of the island.