Not sure I could really define what either of them is, but I can tell them apart because they just feel different. I can tell that I'm romantically in love with someone because it's a feeling that's just not what I have platonically. That's not to say there aren't similarities of course, because there are many. In fact I'd say to me it's kinda like it subsumes platonic love. It has all of that, but also a bit more. I think there's also maybe a sort of "irrationality" or whatever you want to call it to romantic love, like the person themself isn't necessarily in any real sense that different from other people I don't feel the same way about, some unconscious part of my brain has simply happened to confer them with a unique significance.

Also if it's at all relevant I'm asexual so sexual attraction has literally nothing to do with anything here, not that even all allos would say those are necessarily related I don't think.