Defiance vs. dysregulation.
These look identical from the outside and are very different underneath. A defiant kid has weighed the situation and decided the fight is worth it — usually because the fight itself gets them something (your attention, control over an outcome, delay of a task they don't want to do). A dysregulated kid is flooded. Their nervous system has jumped past the point where they can access reasoning, and the yelling and thrashing is what a small brain does when it can't cope. The reason this matters is that the response is different. Defiance responds to structure and follow-through. Dysregulation responds to co-regulation and safety first, structure later. Treating one like the other is a big part of why nothing has worked.



