Digital and physical copies of media content differ significantly in their transmissibility and copy-ability.

For example, creating a digital copy of some content is typically so easy that creating an entirely new duplicate copy is actually how works are transfered. Compared to physical media where creating a copy can be so difficult that copies are shared by physically moving individual copies rather than re-duplicating them.

While many libraries do have significant and valuable collections of digital works, they also tend to have somewhat overrought (or overly trusting) systems for preventing illicit copying.