Documentation
TeX Live Manager has an option to disable install of documentation files, which can take up a significant amount of space. The BasicTeX distribution ships with a limited subset of TeX Live, and excludes documentation. However, you can add packages on an as-needed basis with TeX Live Utility, and it's often desirable to have documentation for the installed packages.
To change the default, choose Configure Documentation… from the Configure menu and toggle the checkbox. If you enable documentation and click Install Now, the documentation for all installed packages will be downloaded. Otherwise, it will only be installed for future update or install actions.
The BasicTeX distribution is popular for laptops with limited disk space, and is approximately 100 MB vs. 2 GB for the full MacTeX installation.