For any given experience level planes assigned to ASW have a larger chance of actually attacking a located sub than planes assigned to Naval Search with the same experience.
That's sort of what it seems is the case, but it looks like it may apply not only to subs, as I'd say probably 40-50% of my planes made attacks on AKs and the like, which is something I do not typically see. I suppose I shouldn't be surprised that they detected other ships (it's not like they are flying with "submarine only" glasses on).
Theoretically, then, if I didn't care about the range it seems like I could set all my patrols to ASW (though I suspect that'd be too inefficient).
So this leads me to the next part: my understanding then is a high ASW skill improves the chances of attacking whatever it is you spot. When the attack occurs, is the hit rate affected by the ASW skill, or does it still use the naval bombing skill?
Still, it is good to know that ASW is still effectively a naval search as well, as it means I'll likely have all my CVEs focus on improving ASW and not worry too much about naval search.