Empty state, no images:

no runnin containers

$ docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

no local containers at all (including not running, and showing the size)

$ docker ps -as

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

not even images

$ docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

Commands

docker ps
docker ps -as    list all the containers available locally  (incl the size)
docker images    list images