In anticipation of a new build I'm trying to gain some knowledge regarding SSDs. I"m way behind on this learning curve.

I prefer to have 1 - 256gb SSD to hold all my programs i.e. Crive. Then a 2nd 500gb SSD for Data i.e. photos, .wav files etc. I will also have an internal HDD for backup. I'm mostly concerned about the hardware inside the box. I have external backups that I make regularly so that does not come into play with this question.

Is it better to run the OS off an M.2 drive or standard configuration SSD? What are the Pros and Cons? I can always research online reviews and specs, but I was just wondering if there is a particular advantage running an M.2 drive for the OS?