For me at least, the Pacific Theatre was a "Carrier War" with both adversaries having a substantial naval force. The goal being to control air superiority whilst battling for pacific islands (which in turn can be considered carriers, albeit stationary ones).
The Atlantic Theatre was an attrition war, with both adversaries having completely different naval forces. The Axis goal was to restrict the supply lines to Britain (itself a stationary carrier of sorts) and hence starve it into submission or at least ineffectivness. In this regard, the U-Boat was the dominant Axis sea weapon. Likewise, the Allies used the Destroyer, and later Air power, with equal zeal.
The two theatres are really not comparable in my oppinion, neither are the general goals and aims of the participating submarine forces.
This is my oppinion, any likeness with anyone else's oppinion is purely coincidental.
