This document describes how you can see whether you are using Windows CE or Windows Mobile on your hand terminal.
When turning on the device, you will default see a start page (desktop or 'today' screen) with a start button on bottom or at the top of the screen.
Windows CE has a Start button at the bottom of the screen and has a Task bar (WinCE 5):
Windows Mobile has a Start menu on top of the screen and uses a 'Today' start screen, and typically shows only 'Calendar' and 'Contacts' at the bottom of the screen (shown are WM 2003 and WM 6.1):