Ha 20mins A?!?!

PSE is certainly more *me* than GFE, it just means giving the experience your client would have if he was with a pornstar. I tend to go with being the girlfriend who happens to also be a pornstar, meaning more relaxed, but actually liking, if not loving the time we have, never shocked at any suggestion, although of course I can always say no, sorry, and have done for A- level for sure.
I don't think there's a definition per se but if one was to advertise themselves as strictly PSE and not at all GFE, then pornstar make up, raunchy, dirty talk, lots of DFK, CIM, OWO, A (at discretion), and actually enjoying sex for real, or making enough noises/having enough orgasms to seem so
