You are not bugging It is difference package between two time points - Point 1 - create initial snapshot (what files, registry etc.) Run installations, modify every setting you want Point 2 - create secondary snapshot (what files were added, deleted or modified) So it will create .exe (or sometimes .msi, it depends on snapshot program) file, that will contain informations what to change. It will save you lot of time - but later, when you will encounter any problem, it is really hard to find out why and whats happening. I am using this snapshot method only when if there is no other solution and I spend a lot of time removing trash from end package. It is not worth the problems it brings with itself... One things that it can be used for is recording tweaks.