Energy is work x time. Remember that the key word is time. Work is the consumption of energy. Energy is what you pay for. The amount of energy in a voltage spike is what does the real damage and the amount of energy a protection device can absorb is the real measure of its worth.
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.