Back in July, at Microsoft’s Worldwide Partner Conference, all the talk was about Windows Azure and the company’s Platform as a Service-based approach to private cloud computing. Steve Ballmer talked about the “dramatic” difference between cloud computing and virtualization, and VP Robert Wahbe said Infrastructure as a Service was “just a feature” of a private cloud.

Those comments showed a major difference between Microsoft’s cloud strategy and VMware’s virtualization-centric, IaaS approach. And Microsoft was delivering a clear, consistent message.

That all changed last week, when we got some news about System Center Virtual Machine Manager 2012.

SCVMM 2012, as senior news writer Beth Pariseau reported, is all about the IaaS private cloud model. Some of its new features will include self-service portals, automated server provisioning and dynamic load balancing. We’re talking classic IaaS stuff right there.

So what happened in the five months since the WPC?

Wahbe acknowledged in July that IaaS is where the market is these days, but he and other Microsoft execs seemed much more focused on their long-range vision at the time. PaaS and Windows Azure still may be their private cloud endgame, with the goal of SCVMM 2012 being to shore up the IaaS “feature.” (That’s something Microsoft desperately needed to do to stay competitive with VMware, by the way.)

But if PaaS and Windows Azure are still the endgame, you’d think Microsoft would tout them more when talking about SCVMM 2012. Sure, the company spent a lot of time on Azure at the Professional Developer’s Conference in Dublin this month, but there’s been nary a word on how the IaaS capabilities in SCVMM 2012 will tie in.

Cloud computing is confusing enough as it is for customers, many of whom are still trying to wrap their heads around basic server virtualization. It doesn’t do anyone any favors to talk about PaaS and Azure at the WPC and PDC, then talk about IaaS at TechEd Europe without saying how they’ll all work together.

Cloud computing is the main theme at this week’s Microsoft Worldwide Partner Conference, and Hyper-V has taken a backseat to Windows Azure. The focus on Azure, a Platform as a Service (PaaS), marks a significantly different approach to private clouds than VMware has taken with its cloud infrastructure model.

And it means that when we talk about the battle between VMware and Microsoft, the folks in Redmond want us to talk less about vSphere vs. Hyper-V and more about vSphere vs. Azure.

Go to any VMware show and you’ll hear that vSphere, its virtual infrastructure product, is the foundation for building a private cloud. But during his WPC keynote yesterday, Microsoft CEO Steve Ballmer said, “The difference between a cloud infrastructure and a virtual infrastructure is dramatic.” (Of course, as our senior news director Barbara Darrow wrote, “That’s what I would say too if I were trying to displace the VMware juggernaut.”)

Furthering Ballmer’s message, Microsoft’s Robert Wahbe, corporate vice president of server and tools marketing, told me yesterday, “The heart of a cloud is Platform as a Service. … Infrastructure as a Service is a feature of a cloud platform, but it’s just a feature.”

Azure has strictly been a public cloud platform, focused on developers, but that changed yesterday when Microsoft announced the Windows Azure Platform Appliance. Hyper-V will be part of the platform, but it’s unclear exactly how much.*

Framed this way, Microsoft’s approach to virtualization and private clouds seems very comprehensive. But it’s a long ways off for most customers — even Wahbe acknowledged that the infrastructure piece, which is VMware’s focus, is “where people are today” — and Azure and Hyper-V are still relatively new products.

Will this approach help Microsoft catch up to VMware? Maybe, but not anytime soon.

*For some reason, Wahbe and other Microsoft execs were reluctant to say that Azure is “based on Hyper-V,” instead saying that its virtualization technology uses Hyper-V, System Center and Windows Server. I’m not sure what the difference is, but apparently there is one. And in case you were wondering, the appliance won’t support VMware, Wahbe said.