Personally, I agree with Britttany; my expectation is that the difference is mostly in the attitude, and the before, after, and in-between parts. With GFE, I would imagine there is a little more in the way of small talk, flirting, seduction, that sort of thing. And with PSE I imagine it's more of "ladies and gentlemen, start your engines" and then ride it until the wheels fall off.
In essence, if this is GFE:
Then this is PSE: