SSD
Uses flash memory technology to implement persistent mass storage
2.5 SSD
Used when replacing a traditional HDD inside of a laptop or small desktop
1.8 SSD
USed insdie of small laptops
M2 SSD
Like a memory chip. small, sleek and light to use in a laptop
mSATA
Allows the SSD to be used as an adapter card that can be plugged into a combined data and power port on the motherboard
Non-Volatile Memory Express (NVMe)
A communication protocol used with the M2 form factor to plug directly into the motherboard