The difference is USB Port and EWAN. Means you can use 3G Dongle later if you want to use at any point of time in future as a backup solution to your broadband.
Also as this router have EWAN, you can use Optical Fibre connections too.
So this is just a future proof router than 8961.
I also thought of getting 8961 first, then TDF members suggested this one and I thought Rs. 500/- extra is VFM for a future proof router. One doesn't plan to get a router in near future if the present one doesn't goes kaput.
So as 3G Prices are going down nowadays, who can say, we may end up using 3G Dongles, 1 Year down the line.
Airtel already slashed it's 4G Prices by 33%, Both Vodafone and Airtel slashed their 2G Prices by around 80 - 90% respectively.
Soon 3G prices will be going down.
Still, if you are sure you don't need 3G / EWAN and you'll never be using one of them, then get 8961.