AHCI and NVMe are data transmission protocol, they work on interface to determine the data transmission method. In addition, there will be other data transfer protocol, such as IDE older (the agreement).

AHCI is technical standards set by the Intel company, it provides a hardware mechanism, allow information communication software and SATA storage devices. AHCI can make senior SATA SATA storage devices activation function, such as support 32 ports, eliminate the master/slave processing, hot plug, etc.

That is to say, the AHCI agreement can play the greatest potential for SATA interface. 32 each transmission queue to make instruction, optimize the disk queue, fast smooth hard disk access data using the NCQ technology, reduce the head movement caused the waste of time.

But the AHCI protocol is designed for traditional HHD, SSD can't exert potential. Even if m. 2 SSD use PCI - E bus, when using the AHCI agreement still cannot read and write speed of more than 600 MB/s. Therefore, the NVMe agreement arises at the historic moment.

NVMe (Non - Volatile Memory express) protocol was first published in 2011. Compared with the AHCI, it don't need to access registers in order, can greatly reduce the delay time.

In addition, it can support 64 queue, each queue can seat 64000 instructions, greatly improving the IOPS capacity. All in all, NVMe can greatly stimulate the potential of SSD.

Let's make a conclusion: if m. 2 SSD only supports the AHCI agreement, the read and write performance is the same as the SATA SSD. If m. 2 SSD NVMe agreement, its performance will be much better than SATA SSD.