Combine them to get... something! Um, something I'll avoid for now until the Cloud of confusion clears up.
Btw, I really enjoyed reading 12-factor app [1] compared to most since the page was a clear description of obviously good practices and debatable recommendations that were at least clear. It was also about apps with a list of 12 things to consider. That fits the name. Page was over 70% specific justifications and technical answers with almost no hype or zealotry. I was impressed the cloud crowd was capable of that. Mainstream needs to do terms and explanations that way more often. ;)
DevOps has as many different definitions as practitioners, and few will completely agree on the same definition.
Cloud is one of the worst frankly, because it is so hand-wavy and it's made it into every day language. My assumption is that this name came from the 'cloud' icon used in a lot of technical diagrams to represent something outside of your control and outside of your scope for the current project. I guess in some ways that makes "Cloud" the perfect term to describe things like AWS/et-al: something that is out of your control.
http://www.sentinelsecurity.us/HYDRA/hydraRTOS/hydraRTOS.htm...
It was a little PCI card. Even so, I'd ask the marketer or developer: could you please draw a logical representation of your client and services with lines showing data flows? Followed by (points) "there's the server(s)." :)