Title explains all
US vs EU are certified to different standards, so the range units (typical vs. rated miles) are based upon different test cycles and constants.
Charging connectors are different. EU specs use a Mennekes connector whereas the US spec uses Tesla's proprietary connector.
Cellular providers are different such that connectivity likely won't work if you move a car from one location to the other.
Probably a bunch of small differences in vehicle requirements, such as functionality of daytime running lamps, requirements around what fog lamps mean and how they work, etc.
Bottom line, bringing a car built for one region into the other region will result in it not being supported and you're ability to use it compromised.
There are all sorts of little differences that you might not give much thought to, such as black seat belt releases vs red ones, or red turn signal indicators vs amber ones. You wouldn't want to be somewhere where the person behind you can't figure out the meaning of a blinking red light on one side, or find yourself trapped in a car, and not having an idea how to get out, because when you look down at the seat belt latch, it's the wrong color so you have no idea what to do.
Other changes I'm aware of:
Headlight assemblies are different (due to focal length and position differences)
EU radio had DAB, US has FM
Rear fog light in EU
I suspect the tires are different to meet EU standards
Lots of labels, screens and manual text differences due to Imperial vs Metric
For the UK - Right hand drive is a big change.
Language shown on screen, and voice commands tuned to local language
Do you know if the rear tail lights are the same between US and EU Tesla's? If, not, what is the difference?
I broke tail light on my EU Tesla, and I'm in a country where SC is not available yet. So I'm trying to find it online, however most offers are from the US.