I agree, Mars just wants your body, for one night only is just fine for him, it's about the conquest, and the notch under his belt.
Pluto wants your soul, he wants to own you, forever. He wants you to be as obsessed with him, as he is with you. As for orgasm, Mars is for the physical release of tension, as Miquar showed, but Pluto is the result of that orgasm, which is impregnation and carrying a new,mysterious human being in a woman's belly for 9 months. (Un)Coincidentally, Pluto is the 9th planet. That baby will grow up to have an orgasm someday which will produce more babies, which will grow up to have more babies, giving birth to nations.
So Pluto is the much deeper result of sex. As u said, it intensifies everything. Sex is not a game for Pluto, it's not just a physical, fun thing, it's a serious thing, involving merging souls, bloodlines, DNA etc.
I would also like to add, that (I think) Pluto rules marriage (as opposed to the common belief that it's 7th house and Venus. I think those rule all basic social interactions. Divorce would move that person from 8th to 7th, from deep connection, to just another person). 8th house rules shared resources, dowries, inheritances, joint bank accounts, etc. It's a very deep complex house. The difference between the 2, Mars and pluto is, Mars is that one night stand u forgot about, Pluto is the one you're connected to forever thru some type of ancient past, and distant future thru the miracle of reproduction thru sex.