Cane Pole is right (as usual). The power rating is a measure of the amount of sound energy and not a straight DC or AC wattage reading from the input power and current.
Also always be wary when comparing wattage as some will spec only peak-to-peak wattage ratings while others spec RMS wattage (P-P should be 8x the RMS wattage value).
What does this mean in simple layman's terms.....as far as what the user's end results would be...??