BizTalk Server 2013
BizTalk Server 2013 R2
BizTalk Server 2013 R2:
BizTalk Server 2013:
The operating systems are the same as BizTalk Server on-premises. The virtual machines in the Gallery automatically include the operating system.
If you purchase an on-premises BizTalk Server 2013 or 2013 R2 license, you can install BizTalk Server on a Windows Azure virtual machine. The BizTalk Server license includes installing on-premises and installing on a Windows Azure virtual machine.
Client computers: Limited to operating systems supported by the Microsoft Azure BizTalk Services SDK:
Installing Azure BizTalk Services SDK
BizTalk Service: Completely managed by Microsoft and hosted on Azure. Users focus on the application needs.