(One of my summaries of the one-day 2016 PyGrunn conference).
What is openstack? A "cloud operating system". Openstack is an umbrella with a huge number of actual open source projects under it. The goal is a public and/or private cloud.
Just like you use "the internet" without concerning yourself with the actual hardware everything runs on, just in the same way you should be able to use a private/public cloud on any regular hardware.
What is RDO? Exactly the same as openstack, but using RPM packages. Really, it is exactly the same. So a way to get openstack running on a Red Hat enterprise basis.
There are lots of ways to get started. For RDO there are three oft-used ones:
TryStack for trying out a free instance. Not intended for production.
PackStack. Install openstack-packstack with "yum". Then you run it on your own hardware.
TripleO (https://wiki.openstack.org/wiki/TripleO). It is basically "openstack on openstack". You install an "undercloud" that you use to deploy/update/monitor/manage several "overclouds". An overcloud is then the production openstack cloud.
TripleO has a separate user interface that's different from openstack's own one. This is mostly done to prevent confusion.
It is kind of heavy, though. The latest openstack release (mitaka) is resource-hungry and needs ideally 32GB memory. That's just for the undercloud. If you strip it, you could get the requirement down to 16GB.
To help with setting up there's now a TripleO quickstart shell script.