Which is faster, NVMe or M2?

I'm curious to know, when it comes to speed, which technology is the superior choice between NVMe and M2? Both have been touted for their blazing fast performance, but I'm interested in a detailed comparison to see which one truly reigns supreme in terms of speed and efficiency. Could you enlighten me on the key differences and advantages of each, helping me make an informed decision on which one to opt for in my next upgrade?