compare indian societies when one compare and contrast the Mauryan and the Gupta Dynasties, which had the most lasting impact on Indian society, and why?
You can find a good deal of information about this topic (and indeed about almost any topic) by searching Google Books. Just go to the main Google page, look at the top, and click the "More" tab. Under that tab, you will see "Books"; click that tab, and Google Books will appear. You can search for books easily, and, as the database grows, more and more information will become available. If you do an "advanced search" (look for that tab in the upper right corner), you can structure the kinds of information that is returned to you (for instance, by date or by thoroughness of the previw).
Here's what I found when I did a basic search of the topic you asked about:
As #3 points out, all civilisations can in part be measured by the way in which they impacted others. It might be interesting for you to consider these two empires in this light, and to investigate further the lasting legacy that each of these two civilisations offered to the civilisations that came after them. Clearly, the fact that you have been given this question indicates that there must be something important about both of them.
One thing that the Mauryan Empire must be noted for as being influential is the first ever unification of large portions of India. They accumulated great wealth and built a marvelous city. However the spies that proliferated across the land make their influence a little less than admirable. Nonetheless, unification certainly had a lasting impact on India.
All modern societies are built on previous ones. I agree with number 2 that zero is a very important concept. The Mauryan Empire does not seem to have lasted long. That explains why it seems to have had less of an obvious impact. The impact is there, in the legacy of the small influences it had on modern society.
These were both so long ago that it is hard to see their impacts today. I guess I'd have to go with the Guptas since it was under them that science flourished more and the idea of the zero was first discovered. It was also during this time that some of the first scientists were known to have used algebra.