I agree with Airport's distinction. A roasting tin usually needs to be deep, although what he calls a grill I might call a rack (see here). However, to complicate matters, you can have a shallow roasting tin, and it might be called a roasting tray.I would say there is a difference. A roasting tin (or pan in my neck of the woods) is usually large and deep so that a roast can fit in it nicely. Some come with a grill for the roast to sit on top of so that it doesn't sit in the drippings. A baking tin or pan can come in many different shapes and sizes depending on what is being baked: cookies are baked on flat and shallow pans, muffins in special muffin pans, bread in long, narrow and deep pans, cakes in round pans, and so on.