One difference between sanding with an air-powered tool and an electric tool is the difference in power supply from a physical point of view. What I mean by this is that with an air-powered DA Sander you will have to contend with an air-line under pressure which is quite stiff. When sanding with an air-powered DA Sander you need to control the air-line in a way that it doesn't rub against the painted panels of the vehicle
and also that it doesn't control or influence the angle of contact between the face of your sanding disc and the painted panel.
By this I mean because the air-line is
stiff, you have to concentrate more on keeping the face of the disc flat against the paint as it's possible for the air-line to exert pressure in such a way as to lift up or push down, or to either side, the DA Sander as it's in your hand.
Note how Shawn has the air-line draped over his shoulder and then curved to his side before feeding into the back of the DA Sander in this picture. While this air line looks flexible, under pressure it is quite stiff and requires you to take that into account for your grip and your arm movement as you're sanding.
This stiff air-line issue is avoided when using an electric DA Sander/Polisher because your electrical cord is
limp in that it is not under high air pressure.
CFM or Cubic Feet per Minute
In order to use an air-powered DA sander you also need a continuous feed supply of compressed air rated at 90 PSI at the gauge. The larger the holding tank the better, for example if you want to sand down entire cars you should have a 60 to 80 gallon compressed air reservoir tank minimum. You can use small portable air compressors for small sections but trying to sand down the average size car hood will deplete the air out of the tank, force the compressor motor to run full speed to try to keep up and still won't be able to keep up and this will show up as your air sander slowing down and even stopping.
The benefit to an electric DA is that all you need is a stable source of electric power and a GFI outlet for
safety reasons.
Note that if you ever use an extension cord with your electric DA or any electric power tool you should always use a heavy duty cord with 16 gauge wire or thicker to handle the flow of electricity to avoid burning up the electric motor in your tool.