Hello,there. i'd like to try to answer your question. In my opinion, if we come across a situation concerned with the ability, actually we can use both 会 and 可以, for example: I can swim. 我会游泳 or 我可以游泳, but 我会游泳 sounds more naturally; but if we come across the situation concerned with the permission,, we should use 可以. for example: Am i allowed to smoke here? 我可以在这里吸烟吗？People never say: 我会在这里吸烟吗？ Hope my explaination helps you a little bit :)