The Aryans and the Ayurvedic armies of the Indus valley were known, but perhaps the largest difference is that Aryans were not seen as superior. A war type clan of people they were, they, as we can guess, did not relish the arts as the Hindus did. So this is the difference.
Yes, this theory is saying that the people that were inhabiting the Indian subcontinent slowly began to spread, and expand their range. They slowly spread across Africa, and continued across the west. This theory explains how all of Europe was eventually inhabited and claimed by the human race in the beginning.
The Aryan invasion theory is simply not true according to all corresponding evidence and research and is simply promoted by a vast array of people due to specific ideological stakes they have in this theory being true. The reality is it is not true and needs to be treated as such.
Current evidence does not support the claim that Aryan tribes invaded the Indian subcontinent in ancient times. Although there is circumstantial linguistic evidence that the so-called Aryans spread their culture across Europe and South Asia, until there is further evidence to support it, this claim will remain an unproven theory.
The Aryan invasion theory does not come to pass on the Indian subcontinent in ancient times. It does not come to pass because it never happened. If you look at all of the discoveries made as of late, you will see that all humans came out of the continent Africa.