I'm actually hyperaware of romantic possibilities. I assume because they could potentially threaten the self-preservational aspect. When people are either formal impossibilities (taken, far away, zombie virus carriers

- this is a particularly tricky category) or emotional/chemistry impossibilities (not attracted to them) I will let my guard down a *lot* more easily.
Oh, I relate very much to this. I'm hyper-aware of those who might be signalling an interest in me, romantically, which is problematic for me if I can't reciprocate (which is usually the case). It's very stressful for me if this mismatch/imbalance occurs.
How do you think the connection differs? Well, you said you didn't really know how to word it, but...try for us?
I'm gonna talk about connection in general - not specific to romance. With romance, it would just be what I'm referring to below, plus a really intense physical attraction/chemistry.
All I can say is that my impression of some of the sx-doms on here, and a few irl I've been a total mismatch with in terms of romantic compatiblity, is that their intensity is focused towards expression of feeling, of vulnerability, a willingness to plunge into the depths of.. whatever.. and expose and be naked and all-known to the other. Much more personalized.. 1:1 intensity, desire to share all inner workings, little to no boundaries or walls, a desire to merge completely with the other person.
A connection for me tends to revolve around an acceptance and sharing of ideas, thoughts, perspectives, and such. Not so personal, not tied to Me necessarily/specifically. Very idea/concept based; not centralized around my own inner workings or emotions. Yes, I express my emotions and personal fears/issues at times, but it's usually more of a declaration...'this is where I'm at'... I don't really want to 'explore' them with another. I basically handle these things in-house and they're not things I tend to want others to help me navigate through, nor do I really think they're pertinent/necessary for others to know about, if they don't really impact the Relationship itself.
Connection is also a blending of personalities... a good back-and-forth, both people giving and taking and interested in one another, really appreciating/caring/loving one another.
I would imagine a dom-sx might get frustrated with me, thinking they're not really seeing 'Me' or getting to know me because I DO sort through a lot of my personal stuff in-house and don't talk it out, and I also tend not to talk about myself or my issues/questions/problems in detail at all - just vague generalities - statements of fact, almost - not really wanting to discuss them - so truthfully I just don't connect that way and my best friends are ones who I have excellent conversations with, however, the content of the conversations just have very little to do with where I'm at internally. Unless I'm wanting input. But it's just input - not exploratory or anything. Almost clinical? Not vulnerable/raw.
If I can share my thoughts/ideas, and be understood/accepted, and vice versa, that tends to equate to a Big Connection. Connection = Intellectual & personality acceptance for me, I think. Big picture stuff; not based on them knowing everything about me or me knowing everything about them. It's like... knowing enough of their general characteristics and traits, but not needing/desiring the nitty-gritty inner workings/psychae. More intuitive? Blah, what a silly ramble this is. And I don't think I'm really getting at the key differences... I can't really put my finger on it, I just know I'm really different from dom-sx, and I think even aux-sx, so my conversational focus/'desire'/need must be quite different too.