After a careful comparison, and not considering regional channels, I came up with the following list of channels that are not available in the two DTH providers:
Channels not available on TataSky
Channels not available on DishTV
NDTV Good Times
Neo Sports Plus
So DishTV offers a lot of movie channels whereas TataSky is offering more in the 'General Entertainment' are and of course Neo Sports.
I could be wrong. If so, please correct me.