I believe the definition of a magazine versus a clip has been given, but I grew up calling a magazine a clip before I knew better from the army. I also used the word ain't back then, funny thing is now, both have seem to become acceptable to use by all but the grammer nazi's.
Or from the NRA website
A device for holding a group of cartridges. Semantic wars have been fought over the word, with some insisting it is not a synonym for "detachable magazine." For 80 years, however, it has been so used by manufacturers and the military. There is no argument that it can also mean a separate device for holding and transferring a group of cartridges to a fixed or detachable magazine or as a device inserted with cartridges into the mechanism of a firearm becoming, in effect, part of that mechanism.