I notice you left your seat to go to the washroom, so I take your exam and write my name on it. I've stolen your exam. This is stealing
Same situation - I look at your exam and check what you got for questions 3 and 4, and copy those answers for my own. This is copying.
There are rules against plagiarism, and if found I would get kicked out of school. However, I did not deprive you of your answers. Your exam is still your exam. You still get whatever mark you got on your own merit.
No surprise you cheat too. I guess bad morals come all across the board. ---