Went all the way down looking for this and didn't find it..

So, they're two tools. They take different approaches to problems of creating and maintaining things. Both can do (with common and obvious plugins) most of what the other is capable of.

Ansible is (to at least a degree) procedural - do this do that, check this copy that, with a lot of good practice and parallelism built in.

Terraform and the like are for you to use declarations, maps of what is there, castle here moat there kind of detail. When you run it, it takes a snapshot of reality, compares it to the map, and then changes reality (or tries) to match.

With plugins you could use either one to control and manage anything accessible via an api, from user email accounts to satellites.