I came across this post written by Kevin Barnes on Agile Processes. A slightly old post and I am not sure what exactly Kevin was trying to convey in this post. However, there was one picture on the same post which caught my eyes and to which I could relate completely.
The picture nicely describes how the two processes are loaded with respect to the Product Design and actual Product Development. Whether it is intended or not, there is typically a lot of upfront design effort in Waterfall. Whereas the Design process is more emergent in Agile. As they say, more important in Agile is the working code.