Apple - List of all packages installed using Homebrew

brew list and brew list --cask

Running brew list will show a list of all your installed Homebrew packages.

In addition, brew list --cask will provide the items installed using Homebrew Cask.

brew leaves shows you all top-level packages. That is packages that are not dependencies. This should be the most interesting if you are using the list to re-install packages.

brew bundle may also be interesting if you are asking because you want to manage your brew installation. This includes casks, which brew list does not. It is aimed at having reproducible Homebrew setups.

# creates Brewfile in the current directory from currently-installed packages
brew bundle dump
# edit Brewfile
# install everything from the Brewfile
brew bundle

You can use the --global flag to operate on your ~/.Brewfile and -f/--force to force overwriting of your existing file (for installation, this will force uninstallation of not-listed packages).