The main difference is that power washing uses highly pressurized steam to do the cleaning while pressure washing just uses unheated tap water, without the help of a heating element.

To clean concrete, exterior siding or an asphalt driveway, you'll want at least 2,000 to 2,800 psi and 2 to 3 gpm (4,000 to 8,400 ECUs).

If you want to clean your driveway quickly and efficiently, use a pressure washer of at least 3100 PSI. Using pressure washers with pressures ranging from 1000 to 2300 PSI will also help you clean your driveway, but it will take a long time.

Think of PSI as the brute force of the water stream. When a pressure washer boasts a high PSI, you can count on it to lift the stickiest and most stubborn gunk. The PSI of effective commercial pressure washers ranges from about 2,000 to 3,000.