CLI client lúc thì được nói là nằm trong động cơ, lúc thì được nói là nằm ngoài

Khái niệm::
The documentation indeed says:

Docker Documentation – 25 Sep 23

Docker Engine overview

Engine

Docker Engine acts as a client-server application with:

• A server with a long-running daemon process dockerd.
• APIs which specify interfaces that programs can use to talk to and instruct the Docker daemon.
• A command line interface (CLI) client docker.

So it includes the CLI, but if you check the Docker Desktop overview, it mentiones the Engine and the CLI although the CLI is not linked:

What’s included in Docker Desktop?

• Docker Engine
• Docker CLI client
• Docker Buildx
  …

You can also install the client without daemon even though it is part of the Engine. I guess the reason is something historical.
Nguồn:: Difference between Docker Desktop and Docker Engine - General - Docker Community Forums