Z170 Fatal1ty supports the 'Killer LAN' network enhancement suite and features like the Fatal1ty mouse port + keymaster.
If you plan on gaming the Z170 Fatal1ty has a few more features specifically designed for precision gaming, but other than that the boards are identical. Same RAM capacity, same BIOS, same internal and external ports.
If you're a gamer get the Z170 Fatal1ty, if you are using your rig for media design just get the cheaper of the two.