What's the difference between platonic and romantic love?

I've actually been struggling with this question for a while now, so I swear it's not ragebait. I just don't really get it (and yes, I'm below, say, 30 years old - I'm guessing this might also be an experience thing). I tried googling it, but it didn't seem very helpful:

Romantic love involves intense passion, desire for intimacy, and often exclusivity, whereas platonic love is a close, non-sexual, and non-romantic bond, typically found in friendships. 

Polyamory exists; asexual people exist; friends with benefits exist. I don't really get it lol.

Other people I've asked have cited the sexual nature of romantic relationships, but (for example) I'd be down to try friends with benefits, if I was comfortable with the other person. The exclusivity seems to be more of a "you're special to me, and you're my favorite" - but if so, best friends...those exist.

Other sources cite dating or casual touching (nonsexual), but people spend time one-on-one with "just" friends? And for close friends, we tend to have contact a lot, just incidentally? So... help.