Don't worry about asking questions mate, no-one here minds. We were all in the same situation once.
A Full Option Tamiya means you get the electronics, muzzle flash, speaker, gearboxes and motors for recoil, elevation and turret rotation. You get everything in the box to build a fully functional RC tank with the exception of a radio and battery.
The non-FO ones have none of that, and are primarily static kits.
Tamiya's are a big investment initially, but will run fantastically when built even stock, and can be upgraded to be even better.
As a starter i'd recommend a Tiger, as its a beautiful runner out of the box, and there are a massive amount of aftermarket parts avaliable for it.
Having spent a lot of money and Time on me Tiger I would have been better off buying the Tamiya kit, upgrading to the same cost as a Tamiya has been experienced by many here so get the Tamiya Tiger I and enjoy.