Geforce gt635m vs geforce gt630

First of all, I want to clarify that my english is pretty bad..

I just want your opinion between theses two laptops, both ASUS. Do not recommmend me any other model, I only can afford those. I would like to know wich one is better in general. I´d like to play some games like BF3, Darksiders II, COD MW. I got a 32'' TV and sometimes I like to download movies (1080p) and watch them on the tv using HDMI connection.

ASUS N73SM-TY028V

Intel Core i5-2450M a 2.5GHz
- Memoria RAM 4GB DDR3 1333MHz
- Disco duro 750GB SATA 5400 rpm
- NVIDIA GeForce GT 630M
- Pantalla 17.3" LED Glare 16:9 HD 1600x900
- Windows 7 Home Premium 64 bit

ASUS S56CM-XX013H

Intel Core i7-3517U a 1,9GHz
- Memoria RAM 4 GB DDR 3 1.600 MHz
- Disco duro 750 GB SATA 5.400 rpm
- Disco duro 24GB SSD
- Grabadora de DVD 8x Super Multi
- Nvidia GeForce GT 635M 2GB
- Windows 8

I know that GT635M is better thatn GT630m.. but how much better is it?
And what about W8? whats your opinion about it? is it better than w7?
And what the hell is "disco duro 24gb ssd" ? disco duro means hard drive.

Thanks for your time and help.