If the goal is only to list all installed packages, pip list or conda list is the way to go.
pip freeze , like conda list --export , is more suitable for generating requirement files for your environment. For example, if you created a package in your user environment with certain dependencies, you can do conda list --export > requirements.txt . When you are ready to distribute your package to other users, they can easily duplicate your environment and its related dependencies using conda create --name <envname> --file requirements.txt .
The differences between conda and pip require a longer discussion. There are many explanations about Kara. This article by Jake VanderPlas is also well read.
You may also find this table useful. It lists the equivalent operations between conda , pip and virtualenv .