A:AnswerThe Asus website states there are two drives in this machine. One is a 1tb SATA drive (cannot tell whether it spins at 5400 or 7200 rpm).
The other is a PCIe Gen 3 by 4 SSD. That I believe is the 128gb drive. The operating system is probably installed on this device making for a significantly faster startup time for the machine.
I don't believe Asus uses a single hybrid drive that combines both SSD and SATA (in other words a drive similar to Apple's Fusion Drive).