Something that comes out of the die in China will look the same as something injecting molded in the US.
NOT true.

The technology is the same.
NOT true

Ultimately, plastic/polymer mags are plastic mags and both designs require ribbing for strength
NOT true.

There are wide variations in mold design based on flow properties of the polymers. Even the same mold, same material, can be very different based on the mold parameters, pre-process, melt temps, mold release methods, and maintenance of the mold. There are thousands of base polymers and even within a family, there are differences. Even within a specific brand name of a polymer, there are typically a dozen or more formulations. Anti-oxidants, tougheners, UV inhibitors, fillers, fiber reinforcing, etc. can all be varied to control the material and the product performance.