is that the same as DRM?

Yeah, more or less.

DRM == Digital Rights Management (interestingly, Microsoft refers to it as ``personal rights management'' within WMP, incorrectly implying that it provides personal rights, instead of that they've been removed by MS.)

SDMI == Secure Digital Music Initiative

They're two different ways to prevent users from using their music as they see fit. DRM works really well since no one is really interested in WMA to begin with. SDMI doesn't, as they can't be bothered to learn how encryption works -- it seems more of a manufacturer SIG than a technical group.