The Gigabyte boards are definitely some of the best out there.
The main differences between the boards are Dual NIC's and Thunderbolt.
Thunderbolt is just a high speed interface, similar to USB, but quite a bit faster. It can be used to drive monitors, to hook an extra GPU up, or to chain multiple HDD's together. In the personal computing world, there are very few situations that can really take advantage of it at this time, so it isn't something that you really need to worry about unless you already have thunderbolt peripherals that you wanted to use.
On the other hand Dual NIC's aren't generally that useful, but if you want to use VM's or dedicate separate controllers to different apps it can be handy to have.