What I always asked myself, is there any difference between the Pro from Ultimate source and Pro from Pro Source? Wiki say Pro is activable in several ways, Retail and VOL, but maybe the Pro-Source Image is only for VOL and from Ultimate is only for Retail/OEM? Im a bit confused. Same question about Windows 10. Thanks in advance for help, guys and girls.
Any 7 Pro can be OEM or VL activated(a.k.a Windows Loader or a KMS activator). The source itself is the same, it's Pro. Only the licensing is different.
Licensing channel is changed with the product key. Only functional difference of the VL edition is the pre-inserted GVLK. That way, such builds can be installed and instantly find the KMS server running in the Enterprise, using DNS entries.