side mounts are usually bolted or riveted to the side of the receiver and can be drilled off. Wire stocks on AK's came in 4 versions, Romanian, Polish, Egyptian and Hungarian and all 4 are different. The Romanian and Polish look very similar but the difference is that the polish version used a button for folding whereas the Romanian one used a lever. The Maadi is similar to the Hungarian version but instead of a T shaped butt stock, had a triangle shaped piece of metal. There is more nerdy detail I could go in to but that's a general rule. One other thing to consider is all wire side folders were built on AKM's and not milled receiver AK's.
In airsoft you can find 3 of the 4 stocks as aftermarket parts (no one makes a Maadi)
EDIT - I forgot to mention East German but these were just a copy of the Polish one