Good question. I've never used a regular one! This one plugs in, and is programmable with the time, etc. I can also saute in it before (or after) using it at pressure, so one pot to brown and cook meat. It also does yogurt and other things, but I haven't tried that yet.
Downside- can't use it when the power goes out! (Which happened Tuesday, when I had planned to make it! ) But, you also don't need a stove, so good for some situations.
If you are happy with your current one, not sure if you need one.