Two Asus Transformer TF300s, same JB version, different skin A friend has two Transformer TF300 tablets, both upgraded OTA to the (apparent) same JB 4.2.1 version, but one has tablet-style notifications (lower right corner) with the Home, Back, and Recent apps buttons left justified on the bottom, and the other has notifications on the top (like a phone), with the back, home, and recent buttons centered at the bottom.   

Is there a setting that controls the notification style, or is there some non-obvious difference in the software versions?
Asus provides two launchers in their 4.2.1 rom - they differ as you descibed in your question. The one with the notifications in the lower right is the same one as used in their 4.1 rom and the one with the notifications at the top is the vanilla Android 4.2 launcher.

You can switch between them at will by opening settings and then navigating to Device -> Launcher (it requires a reboot to switch).