Human's are obsessed with creating order out of chaos. Some people believe each life has a deterministic fate line; others belief they can prevent entropy by writing word documents and expecting other people to read them and act upon them (read: #ITIL). The latest phenomena is the desire to sharpen the pencil once more and define #cloud.
The immediate problem is that the name #cloud was picked for a reason. In the past, technology architects used the icon of a cloud to cover the non-interesting and/or non-focus part of an architecture, an example being an MPLS network provided by a 3rd party. No point in going into detail on MPLS because this diagram is about virtual desktops. Or is there?
I used to work at a company called #Loudcloud. Our business was in providing a service to business where we offered a 100% uptime SLA and other great features (including ability via a portal to push your own code releases), but what we didn't explain was how we did it. That was our business. You bought an SLA, not 10,000 architect hours to explain every minute detail of which compute blade we bought or how we configured it. Our service was a cloud, and the boundary was defined by the service characteristics (think: SLA).
The good definitions of #cloud are those that describe the boundaries. Think NIST. Do they tell you which hypervisor to use when providing a cloud? No. Because a hypervisor isn't required, for one thing, never mind which hypervisor (MAAS and GCE to name two obvious examples of no-hypervisor required). Do NIST tell you to use Puppet, Chef or DevOps? No. They talk about how you access it, and the service characteristics, albeit at (purposefully) abstract level. It's the same for analysts - Lydia at Gartner who does the IaaS MQ talks about the service, not the technology details. This is a Good Thing.
So, the next time somebody tells you a #cloud is defined by some kind of internal characteristic, like using OpenStack, or a specific implementation, like VMware's new Hybrid Service - not picking on them, just selecting from a sea of examples - then you can consider that "advisor" as not really getting cloud. If you ever catch yourself saying "It's not cloud" (and we've all done it, hand on heart) then catch your bad self and think twice: are you being a human control freak just living out your hardwired nature and putting your own restrictions on cloud?