Wattage is a measurement of power. It's the multiplication of voltage and current. While it is loosely associated with how loud a speaker plays, the sensitivity of the speaker plays a major role as well. As very high sensitivity on a lower powered sub will result in more bang per watt, so to speak.

Forget the silly specs. The people that obsess over specs do so because they haven't trained their ears to tell the difference and they desperately want an objective reason to buy something. However, for better or worse, this hobby can not be classified so objectively. It's all about sound which is incredibly personal. Get it in your home and listen to it. Decide which you like better.