I'm a 6w5, married to a 5w4. For nearly three decades she has been saying I get angry for the wrong reasons.
I certainly don't see myself as an angry person, generally speaking. But I frequently react with a burst of anger when I'm blindsided or something doesn't go my way. It's usually some little thing that some people might just laugh over--like spilling coffee or making a blunder in a game. At that moment, I'm infuriated and raging against the universe, insisting that the thing should not have happened. But I also realize it's just a minor upset, so my anger dissipates half a minute later.
My wife, in contrast, sometimes mocks up anger to drive home a point. Or she'll seethe with resentment if she feels she's being mistreated in some way. But the only time she'll get truly, expressively angry is when she's dealing with a gross injustice. I think maybe then she "goes to eight" and exudes some domineering energy.
To me, injustice is usually just the way of the world: it sucks, but you have to choose your battles. And I figure that what goes around will come around anyhow. So, if it's something out in the world, not directly connected to me, I'll just shake my head and shrug it off. I'll feel sad for the victims but not vengeful toward the perpetrator(s).
But if someone insults me or nags at me or criticizes me, I'll instantly react with anger. I may be able to keep it inside--just clench my teeth and keep quiet--but the angry reaction has happened already in any case.
Tied in with that (and maybe it's more because I'm an INFP), I avoid conflict. If I must confront someone, I'll be as indirect as possible, and I'll probably postpone the confrontation as long as possible. That's because once conflict breaks out, it's always very personal to me. It's not just an issue that needs to be resolved or a disagreement that needs to be settled; it's somebody accusing me of being irresponsible, weak, wrong, or defective in some way--and I get very defensive about that.
In (verbal) fights I've had with my wife, she has sometimes told me afterward that I "fight dirty." She's an INTJ--very rational, but also provocative; she considers conflict just a good way to clear the air. But she notices that to me conflict is always personal; so I'll respond to a perceived threat with a personal counterattack. She finds that despicable--perhaps rightly so. But I don't know any other way to behave in a fight, and that's why I avoid conflict as much as I possibly can.
When I was a kid and got mixed up in schoolyard fights, most of the time I was just the victim of bullying. But a few times my anger peaked, and I exploded in violent fury. If the fight was short, I might then win. But if it dragged on, my anger would always dissipate, and then I'd be practically helpless. I couldn't fight at all when I wasn't angry.
I don't know many people of type Eight, but offhand I'd sum up the difference by saying that my Six anger is reactive and their Eight anger is proactive. They'll throw their weight around (gently or roughly) just for the heck of it, whereas I'm meek and mild until provoked. They're also more controlled about it, whereas when I get angry I'm pretty much out of control. Afterward, they remain self-assured; in contrast, I usually end up feeling ashamed for having lost my temper.