Hmm, those are not synonyms. The `PYTHONPATH` env var is just one (optional) way to add additional paths to `sys.path`; a PEP 420 namespace package could have multiple locations on `sys.path` with a completely empty `PYTHONPATH`.

It may be that we use `PYTHONPATH` as a synonym for `sys.path` elsewhere in the documentation, but if so, we are being imprecise and potentially confusing.