Obfuscation is perhaps DRM, but a very specific subset of DRM.

Obfuscation: "I will provide a functional copy of my code that is not (human) reader-friendly; I want people to execute my code but present a barrier to extensive understanding or modification of its implementation."

When someone says DRM, I usually think of its least pleasant incarnations- platform lockdown software that must be installed to play a game or (interestingly) take a test, content that may only be accessed after phoning home and verifying that one is in good standing with the rights holder, etc.

To my mind, JS obfuscation protects IP in a way that more closely resembles compilation.