Differences in Android 2.3 in Samsung Galaxy
Samsung Galaxy S, Galaxy S II and Galaxy Tab have been updated to Android 2.3. But it is interesting to notice that although they all have 2.3, they are not exactly similar.
USB modes
Galaxy S II has Kies mode automatically on, you cannot select it anywhere. You can only choose not to activate it when you connect the usb cable. In USB options there is only Mass storage mode, and you have to select it before you connect the cable.
Galaxy S and Galaxy Tab still have those old USB options: Kies, Media Player and Mass storage.
WiFi
Galaxy S II has also two additional features, which Galaxy S or Galaxy Tab do not have: WiFi Direct and Kies over WiFi.
TeknoMagus 
But if Kies is automatically on, does it still work in Linux. I mean, Kies is Windows software, right?
In Galaxy S II the Kies mode is always “on”, but if you plan to connect the phone for file transfer (mass storage) or tethering, then you should open the appropriate menu in settings. Kies does not interfere with either of these. For file transfers you should activate Mass Storage before connecting the usb cable.
For tethering you should have usb tethering menu open, then connect usb cable and then activate usb tethering (you cannot activate it before.
I thought that with upgrade I get all the features of Galaxy SII. Whats the point in some stripped down version?
Why do they change the menus all the time. In every upgrade the location of some features change