Is Watson a codebase? Or is it just a brand? It seems to me that Watson is basically just IBM's version of AWS/GCE services (at least the non infra ones). But it gets thrown around as a buzzword so often. The marketing makes it look like there's a single AI codebase that can be accessed through a bunch of APIs, but I would be very surprised if that was actually the case.
Both, sort of. There is a "thing" called Watson, which is related to the Watson that played Jeopardy. But "Watson" is also a brand which lumps in stuff that has absolutely nothing to do with the "old" Watson.
To illustrate a bit.. "Watson Health" is (or was) made up of a ton of people and technologies who came into IBM as the result of several acquisitions: Truven, Phytel, Explorys, etc. In many cases, they repackaged stuff from those vendors, gave it a "Watson name" and shipped it. And some of this stuff was literally no more sophisticated than linear regression / logistic regression, etc.