The early imperialism, from the 16th to the 18th century, was characterized by European "settlers." Europeans would go to the Americas (North and South) or Australia. They would then "push aside" the natives, while living there the rest of their lives. Thus, the European colonies (at least the "settled" parts) would consist mostly of European descendants in North America and Australia, or "mixed" European and native people (with a European upper class) in South America.
In the later imperialism, Europeans went to Asia and Africa to "colonize" or rule, rather than "push aside" native peoples. They would spend there "careers" in the colonies, but their goal was to "retire "rich" in their HOME (European) country. As such, they were what the Americans would call "carpetbaggers." These European colonies' populations would consist mostly of "natives."
India represented a transition from one kind of imperialism to the other. It was colonized by the British in the mid-18th century, at the end of the first (settler) imperialism, and ahead of the second (colonial) imperialism.