I watched a video on YouTube recently that kind of made me stop and scratch my head on transformers. Power transformers at least. A guy breaks down and completely unwraps an old Deluxe PT that died. Looking at that, the only manufacturing differences I can think of is wire quality, wire gauge and turns ratios, and laminate bulk/density. For quality, I have to think that any reputable maker that is one of the maybe top 5-6 companies who are usually listed on forums like this are all using similar quality wire. Wire gauge, I can see this being a bigger part of the equation for what separates different models. Obviously, larger gauge wire will have more current handling, and it is going to be more expensive to use. So, somewhere along the line I assume that differences include heavier wire - which makes a bigger wrapping, needing bigger/more laminates to house it - or using more turns (I assume) with smaller wire that is cheaper, fits in a smaller housing, and isn't going to have as much current capacity in comparison. Eventually leading to overheating and failure, which I'm guessing comes from the insulation on the windings getting too hot until a weak spot causes a short. I think I kind of covered the steel laminate part above, but again, quality costs, so the more steel that is there, the more heat it will dissipate. I know there is the "grain orientation and magnetic properties" part, but I have no idea how that works, so I'm going to wrap that up in the quality part and skate on that one. I'm sure I missed some things because it's all assumptions based on this video. I'm not an engineer. Please chime in if I'm just way off base here.