Difference Between US And EU Hardware

just wondered if theres any difference between hardware bought from the US and their EU equivalents.

this is specific to RAM and Graphics Cards, but other info would be much appreciated also.

EDIT: Lets make this a multi subject thread. This here is my upgrade list:

Processor: AMD Phenom II 940 Black Edition Deneb 3.0ghz AM2+

RAM: 2x2 240pin 1066 (havent chosen a particular brand yet)

Graphics: HiS ATI Radeon HD4870 1GB Crossfire Ready (if i have enough to get 2 at the same time...)

Mobo: ASUS M3A79-T Delux

A black suit.

Parts kept:

PSU : 700W something.

HDD : 350GB 7200 samsung something

Optical drives : CD/DVD burner, DVD player, multi card reader

Case: Xclio something something.

My main query is related to wether if i get certain products from the us (gfx and ram, prolly the processor too) do they differ from the EU versions? is there a reason why the UK seems hellbound on overcharging me?

ALSO im looking on advice for Mobo and Ram, since I dont REALLY know enough about them/various companies to make an edumacated guess.