GFE & PSE are equally subjective IMO, but for me, a PSE is wilder, louder and much more vocal, naughty and graphic.
Dirty talking, lots of eye contact and slurping during BJs, loud moaning, many positions, a pearl necklass or facial are relevant, but IMO a PSE delivers on one or more of basically anything a guy fantasizes from a porno, but the thresholds of service will probably diffef for one guy to another.
For me, if it was especially hot, loud and naughty I would categorize it as a PSE, but it is the whole experience I am referring to, not just the sum of x, y or z services. A GFE for me is more tender and predictable, but can also be extremely satisfying.