The bottom half of the rubber grip on the reg is about all that's the same.
The geo has a different type of frame, thus having slightly different grips, the top of the reg grip is different, the air tube is different.
Ofcourse they share the same reg, as it's a very good reg, why would they put a different one in each model?
I fail to see how them refreshing a winning model is down to cutting costs? It's about improving what's already regarded as very good....that's how planet started, and how they continue to make, design, and improve their markers