What's the difference between the P file and the auto file of a camera?

An automatic gear is an automatic gear. In other words, as long as you press the shutter, you don't have to worry about anything. Everything is arranged by the camera itself.

P file is program automatic exposure. The shutter and aperture are arranged by the camera, which will give you a suitable exposure value.

P file is a fool program, and auto is a fool among fools.