Hyper-V and 12 VMs [duplicate]
Solution 1:
If you're planning on running 12 vm's on one physical host , with no previous licensing, Datacenter Edition will probably be a better deal money-wise in the long run. Especially if those are going to be Enterprise versions that you want to run (Datacenter allows you to install any lower version of Server). It also allows you expansion in the future if you decide to upgrade hardware capacity. Hyper-V itself can run as many VM's as you have license for and that your hardware can support. You can also use existing Win client/server licenses if you're migrating those physical machines into the virtual space.
Solution 2:
I'm not sure what you're asking. The 4 VMs from Enterprise means that the single license that you purchase allows for 1 physical installation plus installation of that license in 4VMs. 4 is not the limit of VMs that you can run in Hyper-V, it is just the limit that you can run without having to buy additional licenses.