From: United Kingdom
What you install/update with IS the "Demo Download" - which serves all purposes....
1. On it's own, it's a full Demo
2. With a Purchased key, it's try & Buy
3. As an upgrade of, or with a saved OEM key, it's OEM (and regrettably, since "Express" became an option, many OEMs are supplying this heavily crippled version, instead of the older style "OEM" with only drive and marginal functionality restrictions)
4. As an upgrade of Retail, or with a saved Retail key, it's Retail
They moved to this model with 5.5 - previous versions had a main install and smaller updates - a better model for dialup users, in fact!
In 5.5 (and 6.0) - every "update" is/was a full install!