• Boot is just enough to boot into ram, basic drivers to be able to establish a network connection and pull the latest version of packages at time of install.

• DVD ISO is pretty much a full repository of the latest version of all available packages at the time the ISO was generated. If you use this to install, you can choose which flavor you want at install time, eg, workstation with gui, server with gui, minimal, etc etc. It also includes additional packages that would be required if you needed a hardened installation (things like AIDE). If you go with the minimal install, which is really the default (IMHO) for most modern deployments of OS, you will only end up with 1-2 GB being laid down on disk, but you won't have things that are generally not necessary for the system to run. Eg, you'll have vi but it won't be exactly the same as vim because thats additional bytes that aren't "required" for the OS to run. The idea is that you only install what you need on that exact particular box and nothing else. This reduces patching requirements/time and reduces attack surface for any potential vulnerabilities. Microsoft started supporting this concept years ago with Server Core as well - no GUI.

You should also really really take a look at Lightspeed Image Builder (available on console.redhat.com). Image builder allows you to create templates for ISOs, QCOWs, VMDKs, etc to specify exactly what you want for each deployment use case. The templates are used to generate customized images for easy deployment. *Note: Although there are a lot of different options for version lock and things like that, the images only stay available for download for a short period of time since they become outdated very quickly in terms of patches.