DIFFERENCE BETWEEN DLL AND REGISTRY

Dll stand for Dynamic Link Library. These files are used by applications to perform their specified tasks. In broad sense we can say that, these are the common files used by many applications in order to minimize ammount of disk space they consume on your hard drive and to improve memory performance.
Whereas,registry is an executable file which contains all the information about your Windows OS. This is not shared by number of applications. Every application have their own registry entries.Any change in the registry will corrupt the os.