Difference between contrib nbextension and nbextensions_configurator?

[startakovsky]

What is the difference between line 2 and 3 below?

1. pip install jupyter_nbextensions_configurator
2. jupyter nbextensions_configurator enable --user
3. jupyter contrib nbextension install --user
4. jupyter nbextension enable toc2/main

[juhasch]

The extensions are here and they are basically standalone. To make using them easier there is the configurator menu in this repo.
Basically this means you should do a pip install juyper_contrib_nbextensions and not install the configurator alone.