normal os                       Wince
unlimited process               32 process
non preemptive                  preemptive
no XIP                           XIP

Normal OS(Desktop OS like XP)     Windows CE
-----------------------------     -----------
Not a Realtime OS                 Real TimeOS

non preemptive                    Preemptive

suitable for Desktop              suitable for small  
systems                           gadgets with like Portable
                       .                                
media players,Mobile phones 

Large memory footprint            Small memory foot print.

Normal OS                   wince 
drivers runs under          User space(part of device manager)
kernel space

cannot be customized       customized for embedded application
for embedded application   like mobile phones,thin client...
(exception linux)

kernel - monolithic        kernel- micro kernel