What is M.2 NVMe ?
M.2 is simply a form factor or type of connector for the hard drive. NVMe stands for Non-Volatile Memory express. Breaking this down Non-volatile means that data isn't lost when the device isn't receiving power, memory is just the storage of data. Meaning this really fast data storage running at close to memory speeds.
What is Raid ?
RAID or Redundant Array of Independent Disks is a storage protocol for the system and how it should allocate data to the multiple hard drives in the system.
RAID 1
Data is mirrored on multiple drives, data is essentially written twice once to one drive and then again to a back up drive. Read speeds are again optimized as data can be read from multiple drives at once however write speeds are sacrificed as data needs to be written twice. Loosing one drive would not affect the data providing that the drive with the mirror of the data is still functioning.
RAID 10
Data is split between multiple drives, and each data block is mirrored to another drive. Meaning multiple drives can be lost and the data can be recovered provided the mirror has not been lost. Here write speeds are slow and read speeds are up to two times faster.