[naquaada]

On the Mac, but not on Windows. The Mac has more characters on the keyboard, like the Amiga. They are sorted by the importance of the characters in the country the keyboard layout is made for. This is also for the alternate keys:

1 - no alternate key: small characters, often used addidtional chars
2 - Shift: capital letters, numbers, additional chars

Mac and Amiga:

3: Amiga: Alt, Mac/Mac keyboard: Alt, Mac/Win keyboard: Windows key: more additional chars
4: Amiga: Shift+Alt, Mac/Mac keyboard: Shift+Alt, Mac/Win keyboard: Shift+Windows: less used additional chars

Examples:

In the US and maybe UK the @ was used before emailing, so it's Shift+2. In Germany it wasn't needed at all, so it's AltGr+Q (right alt key) on Windows - you need a big hand span for this. On a Mac keyboard it's Alt+L.
In the UK the Pound sign £ is often used - it's on Shift+3. On a german Mac layout it's Alt+Shift+3 ! So in Windows you don't have it on the keyboard at all, you have to use the character table. The same is with the special signs of danish and swedish keyboards - œæøå ŒÆØÅ, they are directly on the keyboard, I have to use Windows and Shift-Windows on my Mac with a Windows keyboard.
Also the swapping of the Y and the Z is important, in the German langugage the Y nearly never appears, so it's in a place where you are not often while typing. Very different to the QWERTZ/QWERTY keyboards is the french layout; its AZERTY. But there are way more differences than that.
The newest additional key is the € - on Windows it's AltGr+E and on the Mac Alt+E. The crazy thing is, it is nearly never be used - for the Euro normally should be used the international currency abbreviation EUR.