Just want to throw this out there . Windows 10 for Workstation is slightly different beast that supports a couple extra things like resilient file-system.
Microsoft for whatever reason charges more to OEM's for computers with 4 or less cores trying to use this version of Windows 10. Why I don't know.
I don't think there is an actual difference between the two Windows 10 for Workstation versions and seems to just be license difference and any customized machine from an OEM is just going to force you to change to Windows 10 for Workstation for up to 4 cores, if you select that an a 4 core I7 or Xeon. But if you upgrade to a 20 core CPU later, that install should support it and I don't believe you break the licensing (since 4 cores or lower is an increased priced feature).
The one thing I can figure is they want a little extra money from people who are trying to do a barebones File server with the reFS instead of using Server 2016.