BoPs: 3 minute cooldown, very slow. Torpedo Salvo 1. Only summons one per hangar. 17k hull.
Fighters: 30 s cooldown, a bit faster than your carrier. Shoots torpedoes. Four per hangar. 3.5k hull.
Their damage output is more or less the same when they get to fire (4 fighters = 1 bop dps), but since fighters move faster and turn faster, they do more damage in the long run. They are also much easier to replace.
Currently you can summon more than one shiptype from a hangar by replacing the item in the hangar. Therefore, bops are best summoned before combat, and then you can enter combat with fighters equipped. I play with fighters, and so does the other carriers in Murder.