Digital Asset
A digital asset is anything published with a stable identity (a canonical URL, a typed record, a clear place in a taxonomy) that gets more valuable the more the surrounding ecosystem references it. A directory listing, a glossary term, and a well-structured domain are all digital assets. A one-off promotional blog post usually is not.
The distinguishing test is durability: does the thing still pay dividends a year after it was published, or did it stop mattering the day the campaign ended?
In Practice
The Directory entry for a trade school on this site is a digital asset: every article that links to it, every glossary term that references it, and every constellation page that lists it adds to its value. An article announcing a one-time promotion is content; it does its job once.
Worth Knowing
Content and assets are not opposites in practice ... most good content is built on top of an asset and points back to it. The mistake is building only content, with no underlying structure for it to compound against.