need for `git submodule update` over `git pull --recurse-submodules`?

Hello.

I've read [this similar question on superuser](https://superuser.com/questions/852019/git-submodule-foreach-git-pull-origin-master-vs-git-pull-recursive-submodules) but I feel my question is more basic:

From the `git pull` manpage:

    git pull runs git fetch with the given parameters and calls git
merge to merge the retrieved branch heads into the current branch.

    ...

    --[no-]recurse-submodules[=yes|on-demand|no]

    This option controls if new commits of all populated submodules
should be fetched and updated, too.

To keep a cloned repo without submodules up to date I have been using just `git pull`. From the above it seems that I just need to add `--recurse-submodules` to pull all submodules as well.

But if so what is the use of `git submodule update --recursive` or `git submodule update --remote --rebase` or such, which is somewhat confusing to me I'm sorry to say.

Do I need to execute any `git submodule` commands separately even if I do `git pull --recurse-submodules`? All I want is to stay in sync with the cloned repo.