There is no difference at all between this G4 and the other G4s. The only thing Kirby did was slap a slightly different handle label on to identify it as an anniversary model.
I did have one sitting in my garage so I snapped a photo for you. The photo is of the top of the handle label. The bottom looks exactly the same as the others.
the current model at the time that they slapped a commemorative sticker on the handle yoke for. No other changes. Kirby did the same thing in '84 with the Heritage and the Heritage '84. Both identical except the Heritage '84 had a sticker that designated it as an Anniversary edition. Only difference was the decal.