On what do you base this information/ intelligence on that there are more deaths from Maoist attacks than any other violent activities (meaning other terrorist activities[?])?
If you have authentic information, then it would be worth knowing and would be an eye-opener!
There was a time when the it was only this being discussed on National TV. That is why such names like Varavara Rao, Nawalakha et al became known to all!
Well there are many sources including PM Manmohan and HM Chidambaram specifying that the Maoists threat is the biggest threat to India. The main difference between a terrorist attack and an insurgency is that while the govt. is still in a dominant position after the terror attacks, in areas of insurgency the local govt. is non-existent.
Here are some fatalities from 2008-2011 for Maoists Vs terrorist attacks from the SATP. The fatalities include security forces, civilians and militants which gives an overall idea of the amount of violence.
Year --- Left Wing extremism fatalities --- Terrorism fatalities
2008 --- 638 --- 351 (Mumbai attack - 166)
2009 --- 997 --- 2
2010 --- 1180 --- 20
2011 --- 602 --- 42
2012 -- 28 (15+13*) --- 0
* The 13 fatalities are based on the this report as the SATP numbers are updated 15th of every month and does not include this.
India Datasheets - South Asia Terrorism Portal