In addition to the VAT difference, generally the EU has stronger customer protections than the US. In the US there is only 90 days phone support and 1 year hardware support, I think its more than that in the EU (maybe 2 years, etc).
Which brings up an interesting question: buying a phone in US binds you to US terms & conditions?
I know in the case with software and servers purchased by a multi-national, for support in US, you get a US contract and contact US support, as your support in country X is not valid in US. And visa-versa (eg. US person cannot open a support in US for software hosted in country X [per quote, different t&c, warranty laws, etc]).