In application forms, I've only ever been asked either why law or why commercial, so I've always used the same answer and same experience but obviously elaborating a bit more on the commercial aspect if asked the latter. If I am asked why law, would it be acceptable to say that I didn't realise I wanted to go into law at all until I took the module that sparked my interest in commercial law?I honestly don't think you would be ask to elaborate on the difference between the two - I think you would just be asked the questions individually.