Above^ but no terrains plz.
Well, in general, the difference would be "lightmapped looks great", "real time looks okay". Another difference would be "real time is dynamic" and "lightmapped is static". However, in Unity 3, you have quite a bit of dynamic features available even with lightmapped scenes.
You'll find some nice info on how it can look with lightmapping in the Unity 3 Feature Preview - Beast Lightmapping.
I have to admit I haven't found any images like "this is what real-time looks like" and "that's what lightmapped looks like" but such images also could be very misleading because it also depends a lot on the artists' talent. It's not like you just switch from real-time to lightmapped and that's it. There's a lot of possibilities to improve real-time (e.g. deferred rendering allows you to use more light sources; there are also things like real-time shadows and real-time ambient occlusion) ... and creating high-quality lightmaps is an art in itself (which is closely related to lighting a scene, of course ;-) ).
So that should give you a pretty good idea on the difference even when I can't offer any images illustrating the difference ;-)
There’s a video here that shows a scene before and after the global illumination lightmapping in Unity Pro is applied.