At first I thought that greebles were just textures, but I was told that they affect geometry as well. The star wars ship was a basic model. All of the detail (extrusions) were the results of greebles. Greebles are basically just collections of textures indeed, but the term includes displacement maps as well (which affect the geometry). If that is what detail textures are, then I guess they are the same thing.
I am going to try to make an example of how greebles can be used and post it here: