What is the difference between "pressure wash" and "power wash"?

In the cleaning industry, the terms "power wash" and "pressure wash" are used interchangeably with no obvious rhyme or reason. Now over the years, I've heard many newcomers to the industry try to explain it to me as they have explained it to themselves. BUT so far, I haven't heard a single explanation or theory that would convince me that there is an actual difference in the terms.

In many cases, both words, power and pressure, are actually misnomers because in many cases we advocate using the lowest possible pressure with the appropriate action chemicals that will do the hard work for you. And this method helps to maintain the integrity of the surface.