What does OG mean?

^^
More correct.

Refinement:
If a manufacturer goes back to an original design of an older/discontinued model, it may also receive an “OG” label for these more current runs, despite being the same as the older design.

RecRev has done this recently. The original Octave is at least currently back in production. This new production run is being given the OG tag to distance it from the newer Octave 3.