Is it possible for it to be both — to shove a 30 round clip into a 30 round magazine for easy loading.
Not entirely, but pretty much so. The M14/M1A family of military and civilian rilfes uses standard 20 round magagazines. A shooter can load each magazine either by placing individual cartridges, one at a time, into it or by shoving five cartridges at a time into it from a feeder clip. Each feeder cllip is a strip of metal with two lengthwise flanges that fold into it leaving enough space under the rim of each flange for the rim of a cartridge and with enough space between them to contain the bodies of the cartridges. The clip is placed onto a strip of vertical metal attached to the magazine and the shooter pushes the cartridges from the clip into the magazine. IOW the clip is a rapid feeding device for the magazine.