This is a really great question! About the difference between poly and dating.
Me and my partner (mid 20s) went to quite a few poly meetings in Melbourne over a year ago, and met heaps of people who identified as poly. We'd both felt a familiarity with the philosophy behind polyamory - intimacy, openness, honesty. But realised that a lot people seemed to interpret it as simultaneous dating, which now we know wasn't what we were looking for - though we gave it a shot with pretty shitty results. Felt like we'd opened our relationship only to be shut out by new people each other met. It took us a while to work it out because poly people are much more approachable and honest about it, but just because you say it out loud doesn't make it any less the case.
I was thinking back to what attracted me to the idea of an open relationship - it was because we both had friends that we really loved, and we wondered what it would be like to be more intimate with them. Sleeping in the same bed or going away together, or living together, or showering together. Sex and kissing didn't seem a big step from all that, though it seems to cross over some kind of boundary. But the difference with our friends is that they don't try to shut anyone out. I arrange to meet up with them, but if we bump into someone we know or someone else wants to come they can. Which is the same relationship I have with my partner.
We've decided to take sexual stuff really slow, because of some complicated past experiences where it messed with a friend, which then messed with both of us. But I really like exploring everything before that boundary, spending honest, open and intimate time with people. Sitting with a friends head on your lap, sharing beds and skinny dipping, massages, and having an open lounge room where people feel free to come and hang out and stay. Polyamory isn't supposed to be all about the sex, but I haven't met too many people who identify as poly who act that way.
So are we poly or are we something else? I've stopped labelling it, but if pushed I say we have a more open relationship