Die Unterschiede sind marginal, hier mal eine zusammenfassung:
- The pickups on a standard American Strat are Alnico magnets, and the pickups on the Standard are ceramic magnets. Alnico gives a slightly more "vintage" sound, but the Mexican ceramic magnet pickups actually sound a little smoother under distortion that the ones on the US. If you want the vintage pickup sound, you can buy vintage pickups separately... and aftermarket pickups (like Seymour Duncans or Kinmans) are much better quality than even those of an American Strat.
- The necks on the Mexican are American made; the plant in Ensenada does not make them, and they ship them down from Corona, California, where US woodworking is done. The woods are the same on both - alder for the body, maple for the neck.
The bridge saddles on the US models are designed differently, and the claim is made that they offer better sustain. However, keep in mind that the Mexican standards have a vintage bridge design - identical to the design of Fender bridges during the classic 50s and 60s periods when the guitars that the rock stars own were made. Bridge saddle design, from my experience, does little to shape the sound anyway.
There are some electronics differences - Americans have a circuit design called "greasebucket" that lets the tone control roll the highs off differently than the Mexicans - but again, the Mexicans behave the way a vintage guitar would in this guitar, so you may not care.
The finishes on both guitars are "space age" - polyester in the case of the Mexicans, and polyurethane in the case of the the US ones. Some people prefer the old nitrocellulose finishes, but I don't think paint makes that much of a difference on the sound made by the body, if any. A guy at Fender who worked on paint once told me much the same thing.
There are differences, as outlined above, but you have to be a real pro to tell the difference. If you're not a super-discerning listener, you can't tell the difference, and you may even prefer the sound of the Mexican ones (I bought a Telecaster of the standard variety, because I thought it sounded hotter/better than the Highway One I was also considering.)
Wie gesagt - die PU´s sind nicht sooo der Wahnsinn in den Mexi´s, aber abgesehen davon sind die zwar im Detail etwas anders Designed als aktuelle Ami´s, aber Qualitativ auf absolut Augenhöhe....