The distinction, to the extent it exists, would be between the earliest residents of the Indus River valley, the Harappan people; and the later Aryans who moved into India and spread far beyond the Indus valley.
The Harappan people, also known as Dravidians, are the earliest known of the Indian civilizations. Because the remains of the cities are underwater and because their language has not yet been deciphered, most that is known of them is speculation. It is known that they were fairly advanced with class distinction, and eventually encompassed a large area larger than Mesopotamia, in fact covering all of present day Pakistan and much of Northern India. Their religion is not completely understood, but appeared to center on fertility with a mother goddess and a horned god of fertility which resembled a bull. The closeness of this god to Baal, the Mesopotamian god of rain and the storm, has led some scholars to speculate that there was trade/interaction between the two societies.
The Vedic civilization was comprised primarily of the Aryan people who moved into India c. 1500 B.C.E. They were Indo-Europeans, but called themselves Aryan meaning "noble people." They were not indigenous to India, but apparently originated in the Eurasian steppes and overspread much of Europe and parts of Asia excluding China, Korea, and areas to the far East. Whereas the Dravidian people had been primarily agricultural, the Aryans were primarily shepherds, although they did practice some degree of agriculture. They did not conquer the Dravidian people, but apparently mingled and eventually absorbed them.
The name "Vedic Age" derives from the earliest collection of Aryan sacred writings, known as the Vedas. written in a sacred language known as Sanskrit. The term "veda" means "wisdom" or "knowledge." The Vedas has been an important source of information on this time in Indian history. More detailed information is provided in the links below.