The documentation states that "[i]f capture_output is true, stdout and stderr will be captured". This implies a container of some kind. So look to what subprocess.run() returns: "[w]ait for command to complete, then return a CompletedProcess instance". The `stdout` attribute of a CompletedProcess is the "[c]aptured stdout from the child process". 

For example:

    >>> p = subprocess.run("dir", shell=True, capture_output=True)
    >>> p.stdout[:18]
    b' Volume in drive C'

If the output is not captured, the child process inherits the standard output/error files of the parent process, which is typically a console or terminal.

FYI, the `dir` command is internal to the CMD shell in Windows, so it only works with shell=True. There is no "dir.exe" executable that can be executed with shell=False.