Is OEM Windows the same as Retail?

Functionally yes — same OS, same updates, same Pro features. Licensing-wise, no. An OEM Windows license is permanently bound to the first device it is activated on and cannot be moved if that device dies. A Retail Windows license can be transferred between devices (one active install at a time) and tied to a Microsoft account for re-download.

Important: standalone OEM keys are not sold to end users. OEM Windows ships pre-installed by hardware manufacturers under an agreement that prohibits standalone resale. Anyone selling a "loose" OEM key online is reselling something they have no distribution rights to. The legitimate paths for end users are Retail or Volume Licensing.

Still unsure?

Talk to a licensing specialist for a written, signed quote tailored to your environment.