The difference is you can get a cable that's built just as well for a lot less. And you can build one just as well for even less.There are many lousy power cords out there. Some are obviously too skinny for amps and were only intended for low current draw devices such as effects units. Even worse, some fit loosely where they plug into the device -- I had a bad on-stage experience with one of those. Of course, there are the ones that combine both attributes -- absolute nightmares!
So yeah, I could be persuaded to believe that when you compared your ESP cord to one of those crappy ones, you thought you heard a difference.
Or you can do what I do and just sort through your box of crappy cables until you find one that fits well

