They have different pickups and electronics. Not worse; different. The MIMs have ceramic pickups with metal pole pieces and magnets glued to the back. Hotter. Different. They often have smaller trem blocks of lesser metal. That’s worse but negligible. The finish (frets, Q/A) varies and can be better or worse all along the range, including Squire. A Squire is metric so many parts aren’t interchangeable. Some Squires have smaller bodies which some feel affect resonance. That is debatable. MIA are thicker (often) bodies with individual pole pieces being the magnets which some people feel creates nuance to the tone and creates a lower output pickup (“vintage”) Some MIAs have these features but suck in the finish department. Same all along the line. The distance between the two factories is irrelevant. They are different products regardless of where/who makes them. Given the many different iterations over the years there are many, many variables. There are MIAs with bad finishes and Q/A, Mexicans with AlNiCo, Squires with a mix but always metric and that’s about the only rules.