Difference between Linux distros
What is the difference between the various Linux distributions? I know this may sound like a stupid question :) but let me explain.
I know about the different desktop environments, but I also know that installing KDE on Ubuntu doesn't make it into a clone of Fedora. So what are the underlying things that make them different? Could I install and remove software and make Ubuntu into Fedora? I am fairly new to Linux, and the reason I started using it was because of the customizability. I am the type of guy who edits system files to make my Windows login screen different, so don't spare the technical aspects :)