I really don't think the difference is that stark. Sarah and I discuss things all the time. Decisions come out of those discussions. Usually we've discussed it to the point that we've taken into account both people's perspectives and agree on the outcome, so you could call it a "joint decision" as we both came up with it. But then again, often I've made the final call, even though we both are in agreement, so you could equally well call it my decision. And when we aren't in agreement yet have to make a decision anyway, although it's my call, at times I'll run with what Sarah wants if she feels more strongly about it than I do. There really isn't a clear line between what "we" decided and what "I" decided - yet ultimately I'm in charge.
In my opinion that ambiguity is healthy. When there is no ambiguity and it is really obvious who is in charge, because someone thinks this is important enough to keep talking about, that's a red flag in my opinion. Whether that's a man who keeps talking about the fact that he's the boss, a woman who feels she has to keep talking about submission all the time - or a woman who keeps asserting that her man is not in charge, or a man who keeps saying that he isn't - in all such cases the very fact that they feel a need to talk about it a lot makes me suspicious that things are not going well in their marriage. Because if things are healthy, and everything is working smoothly, it's just not something you think about much.