These boards uses 12-phase power design with a water pump header onboard having one M.2 slots each of them along with SATA III 6GB/s ports but also surprises us with another M.2 Key E Slot.
Having PCI-E connections identical , there are three PCI-E x16 slots protected and well covered with steel plating.It also has two PCI-E x1 slot.They decided to put two Gigabit NICs on each of the boards.They differ mostly in the aesthetics department , UEFI Bios,Audio and USB.
The ASRock Fatal1ty X99 Professional Gaming i7 is more expensive have black color scheme with few white and red LEDs.
Where as the Taichi has many printed gears on the whole motherboard with a black and white scheme with matching UEFI bios.
As mentioned the USBs differ but both have USB 3.1 Gen 2 controller a and Asmedia which will be powering the Type-C and the Type-A ports.And where they differ is that the Taichi has 5 USB 3.0s and 7 USB 2.0s whereas the Fatal1ty has 8 3.0s.
They have opted Realtek Audio for Taichi and SoundBlaster for Fatal1ty.
Some details are: