What is the purpose of Air Carrrier Plane?

[jermanie]

How are they different from Bombers? Are they worth it? Also, what is the purpose of Heavy Fleet and Carrier Ships? Are they worth building? I seem to think that Submarines are good enough.

[rjh1971]

CAGs are the ruler of the seas, they can wipe of enemy ships they have increased ships attack and torpedo attack values compared to tactical and strategical bombers.
Playing as the WA and Japan they're essential, not if you're playing with Russia and Germany.
CAGs need CVs in order to be embarked, HF are not worth building they good for shore bombardment and striking enemy vessels if unprotected by CAGs.
Subs are good for hunting Transport Fleets, you need to keep improving their evasion and attack levels or the enemy ASW will end up hunting them down.