Quick Answer. A tantrum is goal-directed: your child is upset, still in control, trying to get something. A meltdown is neurological overload — your child has lost control entirely and cannot stop, even if they wanted to. The strategy that works for one makes the other significantly worse. Here's how to tell them apart in 5 seconds, and exactly what to do next.
"If I gave them exactly what they want right now — would they stop?"
"You're really frustrated right now. You wanted that."