Energy is watts x time. The amount of energy a surge protector can absorb without damage is a fixed value determined by the size of the parts the designer specified into the surge protector when he designed it. Restating what we've learned. But look what a clever advertising copywriter can do to the spec game. Everyone has bought a light bulb.
Bigger bulbs give more light.
Bigger is better. The problem is they are using different time bases for the surge duration. A typical surge duration is 100 microseconds. Some manufacturers use one millisecond. Other manufacturers use one microsecond.