'Xcode' is a (integrated development environment, ide) application within a set of 'tools' identified as 'Xcode tools'. 'Xcode' (the ide application) and its related 'tools' (or their respective folders) reside in the '/Developer/Applications/' folder.
You can manually drag 'Xcode', 'Interface Builder', etc. from the '/Developer/Applications/' (or related sub folders) folder onto the 'Dock' for quick access, to the specific application.