After using a couple models from different regions and build dates, no, they're not the same.
The most striking difference between EU and JP is the screen's refresh rate. The EU ones have awful ghosting. Most people don't notice it, but I'm pretty sensitive to it and games like Bleach DS are almost unplayable on an EU DS. However the early EU models didn't have the problem- I think they got downgraded somewhere along the line... Europe has low standards, apparently. :roll Also the JP model feels "tougher", the buttons have a little more click to them and touching the screen is more of a "tap" than a press. Hard to explain.
I could be wrong though, need to test a bit more but they're definitely not the same.
While this isn't about the US one I'm just saying there are differences between regions.
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