A hard disk drive is mechanical.
With cache, they are good for short bursts of 20-40Mbps; but for sustainable transfers you are going to see 8-12 Mbps, depending upon the size of the disk, and physical location on the disk, the data is being written
The disk is circular, so data at the inside of the disk is marginally faster access.
If you want/need faster sustained data transfers; I suggest solid state drives. They are about 20x faster, with the newer ones being even faster
Both drives are solid state and capable of Sata 3 speeds. They are both running at Sata 1 which is 1.5 mbs speed.