In Israel we have the option of choosing Macs with US layout or keyboard layout. What changes is mainly the enter key on two rows of the European models, the character "`", and the characters next to the shift keys.
Indeed, that's my point. What you've described (Mac US vs Mac UK) less significant than comparing a UK Mac and a UK IBM keyboard.
I'm not suggesting that a UK Mac keyboard is "the same" as a US Mac. Just that for someone used to a UK IBM keyboard, a UK Mac keyboard will feel different (and visa versa for Mac users switching to IBM keyboards).
