2.) Gigabyte B250m d3h
- If you want to use a Kaby Lake CPU. You will need the Gigabyte B250m d3h. As it will have the required BIOS. The ASRock will likely need a BIOS update which must be performed with a Skylake CPU.
- USB 3.1 vs USB 3.0
- 3 System fan headers vs 2 system fan headers
- More interanl USB 2.0 Headers
- Internal USB 3.1 header vs USB 3.0 header
- SATA Express support (not that anyone uses it)
1.)ASRock H170m pro4
- RAID support
- 2x PCIe x1 slots vs 2x PCI slots
- Intel Smart Response Technology support (no one uses this it basically allows you to make a hybrid drive out of an SSD and hard drive like Apple's Fusion drive)
- Intel vPro and SIPP support (these are things some IT departments might care about)
Everything...