Nope, that's not it, Ooh-Aah2.

The differences are these:

1. India has its share of fundamentalist Hindu terrorist groups, and fundamentalist Hindu terrorist incidents, but those incidents effect people that you and most of the West couldn't really give a shit about (they are mostly Muslims, Christians in India, and Sikhs), so you never hear about them.

2. Afghanistan's civil infrastructure was completely destroyed and people had no means of maintaining any kind of continuity in their civic life and in their civilization. India's civil infrastructure was never destroyed, and the continuity of their civilization was never fully disrupted. So even though both countries have problems with fundamentalist perpetrated terrorism, and even though the fundamentalist Hindus who are intolerant of people who are not Hindus are becoming more and more powerful in the Indian government, they haven't yet taken over all of it, as happened with the Taliban. In Afthanistan, the Taliban, terrible as they were, created order out of the warlord driven chaos that existed there before they took over.

3. Terrorism is not something that is practiced randomly, despite what many people might like to think about it. Terrorism is designed to produce a specific result, and the targets of terrorists are chosen with specific strategic goals in mind. In the case of fundamentalist Muslim terrorism, the targets are chosen to promote the goals of removing/ending the interference of countries like the US, Britain, Israel, (and in the case of some countries, also France) in the affairs of Muslim countries that is ongoing and that is seen as a current threat to the interests of these countries. So this conflict would naturally involve both Muslim countries and "Western" countries.

British colonial rule promoted divisions within India. It promoted stratifications and divisions that were not so much of a problem for India prior to British colonial rule, but which have become problems that have been continually increasing in severity over the decades since the end of British colonial rule. So the effect has been that the strategic targets of terrorists in India are, for the most part, other groups within India, rather than groups outside of India. The exception to this being some conflict between India and Pakistan over the disputed territory of Kashmir. There is no ongoing terrorism by people from India towards Britain because Britain is no longer any kind of threat to any of the different groups within India.