What is the Difference between Windows Azure and Office 365?

Something that I see coming up more and more often recently is the question as to what the differences between Office 365 and Windows Azure are and how the two relate to each other more exactly.

Windows Azure and Office 365 are cloud based services. The components of Office 365 rely on Windows Azure Active Directory services on the back-end although Windows Azure is much more than just Active Directory Services.

First let’s discuss at a high level the different types of cloud services that are available. In the cloud the following services are available:

  • Software as a Service or SaaS,
  • Infrastructure as a Service or IaaS and
  • Platform as a Service or PaaS

Wikipedia defines each of these as follows:

Software as a Service (SaaS)

In the SaaS model, customers are provided access to cloud-based application software, services and databases on a subscription or pay-per-use basis. Providers manage the infrastructure reducing the dependence and need for on-premises infrastructure. This has the effect to significantly reduce infrastructure costs for the customer and simplifies maintenance and support of the application, service or database as well. SaaS is sometimes referred to as “on-demand software”.

Infrastructure as a Service (IaaS)

IaaS clouds offer computing resources often built on pools of hypervisors including Hyper-V or Xen or KVM or VMWare although they can also come in the form of physical resources as well. Virtual-machine disk image libraries, raw (block) and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles are resources also provided in this model.

Platform as a Service (PaaS)

In the PaaS model, cloud providers deliver a computing platform, typically including operating system, programming language execution environment, database, and web server. Application developers can develop and run their software solutions on a cloud platform without the cost and complexity of buying and managing the underlying hardware and software layers. With some PaaS offers like Windows Azure, the underlying computer and storage resources scale automatically to match application demand so that the cloud user does not have to allocate resources manually.

Office 365 is SaaS providing an online version of the Office suite (Word, Excel, Outlook, PowerPoint, One Note, Access, Lync, etc.) along with SharePoint, Lync and Exchange.

In contrast, Windows Azure is IaaS and PaaS. Windows Azure can be divided into Compute, Data Services, App Services, Networking and Store.

  • Compute:
    • Cloud Services
    • Virtual Machines
    • Web Sites
    • Mobile Services
  • Data Services:
    • SQL Database
    • SQL Reporting
    • SQL Data Sync
    • Storage
    • HDInsight
  • App Services:
    • Caching
    • Service Bus
    • Windows Azure Active Directory
    • Access Control Service (ACS)
    • Media Services
    • Content Delivery Network (CDN)
  • Networking:
    • Virtual Network
    • Traffic Manager
  • Store

As you can see, Windows Azure is much more than the Active Directory backbone supporting the components of Office 365. Microsoft has released a Windows Azure Poster that describes each of these sections in detail and is quite helpful when comparing and contrasting not only the differences between Office 365 and Windows Azure but in describing all the components and offerings of Windows Azure. The poster can be downloaded here.

As it relates to IaaS, Windows Azure is Microsoft’s Operating System for cloud computing. With the PaaS model, Windows Azure can be used for development, service hosting and/or service management.