I think it might be the marketing talking, but Frames per a second and Samples per a second are pretty much the same thing. If you wanted to get technical I'm sure you could argue the need for a difference, maybe due to the way the sensor measures (FPS is a whole image capture, where as SPS is just a small sample of a full image), but for simplicities sake it would be nice to have them both called FPS, as most gamers already understand it as a suitable unit of measurement.
The laser clearly leads when it comes to performance here. Over six times more samples/frames taken per a second than the optical, but this has to be processed by the on-board chip set, so performance gain gets scaled down a little bit. The inch per a second is a good indicator of just how fast you can move your mouse before it can no longer track accurately.
G-force ratings may seem like nothing but a little bit of marketing too, but it's useful to tell us how good the image processor is at coping with the mouse moving at varying velocities, so you can be sure that when you need to turn on a dime and smoke a n00b, you're covered.
CPI; this is where the two mice get a little bit different in terms of usage and not just specifications. The Optical is adjustable from 400-1600, making it quite the sensitive little rodent. The laser steps it up by having a full range of 1-3200, a trifle over-kill, but it's nice to see that you have full control over the settings.
The reason for the adjustable CPI is so that you can leave your game's mouse sensitivity multiplier set to 1 and just ramp up the mouse hardware to the perfect level. This is so that you get an equal sensitivity across all games. The laser here clearly caters to the gaming crowd with the higher CPI, and while average gamers like me could be content with the optical, the laser definitely gives an edge if you are an FPS'er.
The two extra buttons on the side of the mouse act as forward and back in windows mode, but they can be assigned in game to any desired function as expected. The button on top under the wheel is for on the fly CPI bumping, allowing switching between two presets, indicated rather nicely by a white led lit window in the side.