The differences between these and the most recent 18-55s is that they now use a stepper motor for focusing instead of the silent wave motor. This saves space (the SWM being a ring motor, it fits around the inner barrels and the outer barrels must cover it, requiring a certain amount of space) and may have other technical advantage over the SWM. One I can think of is that occasionally an SWM motor will squeal loudly. I expect the stepper motor to be quieter.
I've seen this new lens and it is VERY compact. Really good for travel purposes, and I'm going to bet that the optics are at least as good as the last generation.
I will probably buy one of these lenses. It seems like it's too handy at its size NOT to have it in your DX camera bag.
Now let's see how long it takes for them to release an FX equivalent. AF-P 24-80mm, F/2.8. Yes, please.