NVM Express is a logical device interface specification for PCIe storage, for flash memory in the form of SSDs. It is a faster, albeit more expensive, interface compared to SATA. Today's NVMe drives achieve speeds up to 16 GB/s, with 32 GB/s on the horizon.
SATA is a computer bus interface introduced in 2000. While cheaper and more compatible than PCIe, SATA is a slower interface. SATA 3.0 is the most common form of SATA SSDs, with a practical transfer speed of 4.8 Gb/s, or 600 MB/s.