Consider this hosting models chart by AMIDO:
The Functions as a Service (FaaS) stage let a user to manage only applications.
How these "applications" (say WordPress/Drupal/MediaWiki application) defer from containers of them as can be utilized in Containers as a Service (CaaS) stage?
I ask this because one can have a WordPress/Drupal/MediaWiki container as well and easily transcribe it into an applications.
If I understand the difference correctly, in FaaS, the company will indeed transcribe containers into applications but will do so themselves without letting me do so with, say, Docker (they will likely give me a GUI to query their system to do so (likely with Docker) but not to me my via installing and using Docker traditionally.