One reason I love World Machine is for the ability to create, or sculpt the exact terrain or terrains you want.
One of my favorite methods is to create a foreground, and then add one or more background mountains (or whatever) kind of in a way you would place them in Vue.
Only in World Machine, you can create all those WONDERFUL maps (for each foreground and background) that you can then use either as color maps, or as masks for the placement of materials or plants etc......
It just opens the door to so many more possibilities.