The ISO file itself is often identical for Standard and Datacenter (both are included in the same disk image). The difference lies in the product key you enter during installation. Thus, a "Windows Server 2012 R2 Datacenter ISO download" is typically the same file as the "Windows Server 2012 R2 (all editions)" ISO.
Microsoft rolled out a "System Update Readiness" ISO that includes all updates up to April 2014. This is often the most stable base ISO. Windows Server 2012 R2 Datacenter Iso Download
| Feature | Windows Server 2012 R2 Standard | Windows Server 2012 R2 Datacenter | | :--- | :--- | :--- | | | 2 Hyper-V Containers / 2 VMs | Unlimited VMs | | Software-Defined Networking (SDN) | No | Full support | | Storage Spaces Direct | No | Yes | | Clustering | Up to 64 nodes with standard features | Full cluster-aware updates & storage replication | | Target Audience | Physical servers, small deployments | High-density virtualization, cloud hosts | The ISO file itself is often identical for