And if you want to hear the difference at length, ask any poly person.
Wait, you have to ask? I've never had that problem. /s
I very much enjoy the fantasy of one male with a (sometimes literal) harem of women, with a healthy dose of mind control mixed in (and other kinks, when I'm not on this site). While certain aspects of the poly lifestyle might seem to resemble that, in the end it's a very different thing. And obviously the poly stuff comes up a lot in these comics (early on in THK, for example) but for me that's of limited attraction... too "real" to be a fantasy, or at least to take it as far as I would like this stuff to go. The power/freedom imbalance in a (fantasy) relationship where one man has multiple women that he doesn't share (with other men) but who is free to pursue other avenues or expand his harem adds a lot of heat to a story. The idea that a woman could be mc'ed into *wanting* a relationship like that adds another layer of fun/sexiness to it.
So Weston? No animus against him. I think he's kind of funny; a bit of comic relief. And I'm glad he's got his gf and his poly relationship(s). But I really hope that Adrian's women stay Adrian's, exclusively (barring Caitlyn's inevitable misadventures), is the main thing.