Python: pyenv vs pyvenv vs venv vs virtualenv

What's the difference between pyenv, pyvenv, venv, and virtualenv?

pyenv - a 3rd party tool for switching between multiple versions of Python (e.g. change the global Python version between Python 2 and 3).

pyvenv - a built-in command line tool for creating “virtual environments”. It helps separate packages dependence between projects. Added since Python 3.3.

venv - a built-in API module for creating "virtual environments". Added since Python 3.3.

virtualenv -a 3rd party tool for creating "virtual environments".


Ref:
Python: pyenv, pyvenv, virtualenv – What’s the difference? | Abu Ashraf Masnun
PEP 405 -- Python Virtual Environments | Python.org