how does NVMe work?

so I haven't bought a notebook for 2 years and feel a bit oudated.
I've seen so many m.2 standards that I don't know how they work. I've read that NVMe is the new thing that delivers great speeds. but how to know if a notebook has NVMe? if it has an m.2 slot does it mean that a NVMe SSD will work on it at lower speeds even if the notebook doesn't support it?
what are the cheapest notebooks with NVMe?
what's the difference betweem a M.2 PCI-E SSD and a M.2 NVMe SSD?
and what about all the sizes?
I'm really confused. can someone explain it to me? tkx.

 

Believe you are trying to understand PCIe NVMe and SATA III because PCIe uses NVMe controllers for high-bandwidth data transfer. In other words, PCIe allows for SSD's to have transfer rates of up to 3GB's per second (Gigabyte, not Gigabit), while SATA III is limited to roughly 600MB's per second. They're using PCIe lanes for storage devices, which is one of the reasons I chose the 6850K over the 6800K.

In day-to-day usage, you will not notice the difference between the two. The main benefit is space saving (inside laptops) and reduced power consumption. However, you will notice it if transferring very large files, assuming both your write and read devices are PCIe.

 

Well said! Couldn't say it better myself!!