There can be too many variations. You would need to provide a link to what exactly it is you are comparing.
Obviously, "Managed" means management is included, but what that kind of management depends on the provider. For example, some support 3rd party scripts whereas others only support the network/hardware and maybe the OS only.
Cloud VPS must be using some type of virtualization which may either help scalability wise, provide better uptime or a combination of the two. Could also have other benefits.
Cloud VPS ram must mean it is a VPS that includes a lot more RAM e.g for a backup server because it can use a lot of RAM.
Unfortunately the differences sometimes is not as much as it would seem.
Some hosting providers use the names interchangeably to mean the same thing, and use it as marketing terms.
Only way to be sure is to read their description and contact them for clarification.