I'm an 8, either sx/so or so/sx.
I will say it takes a lot for me to experience anxiety - and anxiety doesn't even seem to be the right word. I'd sooner call it stress. Anyway, it takes a lot for me to get stressed out. I'm also not typically paranoid or "worst case scenario" type of person, unless I've been stressed for a PROLONGED period of time (that's when I know I'm disintegrating to 5). It isn't the same sort of paranoia as what a 6 experiences. I'm married to a 6 and I have to constantly tell her to take 13 steps back before we start worrying about shit that hasn't happened.
I also work with an extremely unhealthy 6 who needs recognition for doing what she was hired to do. She had a breakdown at work yesterday because she didn't feel as important as everyone else, felt like she was at the bottom of the "totem pole", and that she wasn't being appreciated. I have a whole host of issues with her that have nothing to do with type, so I want to stress that she's unhealthy.
Even when I'm at my most unhealthy, I don't want random praise for doing what I'm supposed to be doing. I don't need someone blowing smoke up my ass.
So one thing that separates these types is self-sufficiency. I don't really need outside approval, reassurance, encouragement, or validation. I'm not saying 6s can't be self-sufficient, but often they lack trust in themselves and will question their own judgment. They seek out another person to assuage those insecurities or bolster their confidence.
6s and 8s can both have trust issues, but they manifest differently. 6s tend to be more distrustful by default. I'm not distrustful, but I'd still rather control and handle projects myself. I know I'll do it right and involving other people just complicates shit. I trust myself to do it right and do it well.
The biggest misconception is the idea of 8s needing no one. This simply isn't true unless you have some sort of pathology. 8s are very protective of people in their circle, especially if they are satisfying their instinctual needs and the 8 is more integrated.
From a morality standpoint, the topic of "fairness" is something I notice typically if someone is getting screwed over or taken advantage of. I don't tolerate that bullshit. I'll also step in if someone is being treated badly, or getting unjustly blasted by someone who has a shitty argument. It's always fun to step in and even the playing field by annihilating whatever point the other person made.