How to choose?

If you wish to install ReactOS on your machine, then Boot CD is the right option for you. Boot CD will direct you to a setup environment, please follow the instructions given on the screen. Live CD is useful if you don't plan to keep ReactOS on your computer for a longer period of time. It allows you to explore ReactOS in a temporary environment that will be reset in a restart. Please note, that ReactOS is still in alpha and gives no guarantee of stability, safety of your files or working at all.

What do I do with this?

ReactOS Wiki is an ideal source of information, it will help you setup ReactOS in your desired environment. "Installing ReactOS" page should help you get started.

Additional downloads

Source code for ReactOS 0.4.14

ReactOS Torrent downloads via FOSS Torrents

Nightly builds

If you wish to download the bleeding edge versions of ReactOS, then nightly builds may just be your cup of tea. However, they do come with a catch; you're more likely to encounter regressions at the cost of new features. These are built on every commit made to the GitHub master branch and run through extensive tests on the Testman.