They are not the same actually 컴퓨터를 써도 돼요 It's okay for you to use the computer V도 돼요 This is used when you ask for permission to do something. You can also reply back with the same expression. 화장실에 가도 돼요? "may I go to the bathroom" 네, 화장실에 가도 돼요 " yes, you may go to the bathroom. 컴퓨터를 쓸 수 있어요 I can use the computer 할 수 있다 This means that you are capable of doing something. 이 컴퓨터를 쓸 수 있어요 I can use this computer (because I know how to type, it's not broken, or any other reason)