Baseboard molding can be tricky if you are not sure how to cut the corners. Each type of molding is different and will require a different type of corner cut. Baseboard molding is no different as it requires its own specific type of corners. It is important to understand what to expect out of each one.
Whenever you are working with outside corners, it is recommended that you use a miter corner. You will need to get a miter box as well as a backsaw to be able to do this properly. Cope corners are not recommended whenever you are working on outside corners.
An inside corner will require a cope joint. This type of cut is going to need to be blunt and the molding should be overlapping itself. Make sure that the overlapping parts curve together perfectly or it will not work.
The end result is that both cope and miter are necessary for a project whenever you are working with baseboard molding. It simply depends on the type of corners that you are working on. However, if you only happen to have one type of corner, then you will only need one of these.