You probably see a variety of overlapping terms to describe the management of content. One example is "assets" -- aren't all content items assets of one kind or another? Like most of the industry, though, we refer to "assets" when talking specifically about rich media. So for example we use the term Document Management for things like Office files and scanned forms, but when talking about rich media (video, audio, images etc) we refer to Digital Asset Management.
It may seem a minor point, but as we state in our Digital Asset Management Report "...in the DAM world, content is a bit more abstract: it's something with value, hence an asset. The distinction is subtle but important...." Important, because it clarifies that with DAM you don't manage junk; you only manage items that are of value.
There is something to be learned here in the document world. For years I have advised clients that they should only focus time and money on business-critical documents, and point out to them that the vast majority of electronic documents sitting on their current system are junk, outdated, or in some other way redundant. Though far from scientific, those firms that have analyzed such situations typically report that 10% or less of the documents within their systems are actually of any value to the business.
To be clear, I'm not suggesting we come up with another acronym definition. However, I would like to see us all think more clearly about what is worth managing, and more clearly delineating between junk and stuff that actually has business value. In a broad sense, all information management activities be they related to web, e-mail, records, or documents should at heart be "Digital Asset Management" activities.