Theres no difference, though some people think there is. PE stands for polyethylene, a type of plastic. All braids/super lines are made out of spectra or dyneema which are two brands of polyethylene (or ultra high mollecular weight polyethylene if you want to be precise). They're made via difference processes, but the end fibres are pretty comparable in properties.

There is a fair bit of variation between braids though. You can get different weaves, different coatings, etc. Generally when people refer to PE over braid they are usually referring to japanese braids. Usually they have a higher weave (rounder/smoother) and are often thinner and tend to be softer with less coatings. E.g. ygk, varivas, some daiwa braid. They're more often available in colour marked as well. Something like tufline is still a form of PE, but most people dont call it that. It tends to have a lot more coating and feels a bit different. Underneath its the same stuff though. Even fireline is PE, its just fused after being braided which makes it feel different (stiffer and more wiry).

PE can also refer to the size line. Basically its the diameter of the line (or area really if you want to get technical). So PE2 line is thinner than PE5 line. Generally PE2 is around 20lb, PE5/50lb, etc, but thats just a general rule. You can get braid thats PE3/50lb or PE5/80lb for example. Generally, PE ratings are only used for japanese braid (hence why some people think PE=japanese braid). The PE rating was taken from silk measurements, and in japan now can even refer to mono (e.g. 2.5 mono line is the same diameter as PE2.5 braid, but not as strong). Because theres a missconception PE5=50lb and so on in australia, some manufacturers call their braid PE3 when really its a little thinner (but its 30lb rated). In japan, most PE3 will be the same diameter though.

Thanks for that, it's making sense now.

Wow, you know alot about braid haha