@tjs1295, my non-expert take:
Without hearing or seeing the context of what Joel was trying to correct with a specific skier its tough to know, but it is quite possible you heard both right and the advice is somewhat inconsistent. There are different schools of thought in this sport and Radar and Connelly have a different design philosophy on what they want the ski to do. In other videos, I have heard Joel state that the goal of the Connelly line is to ride deeper in the water but to hold speed. He has been working on the line for a long time and I suspect it reflects what he is trying to do on the ski. And the GT/GTR/DV8 is a skinnier ski than the Vapor. I own both skis and they are very different animals. The design philosophy of the Vapor seems to me to be reflected more in what Rossi and Trent are talking in about in all their episodes. Get up over the top/front of the ski and step on the gas.
I would love to hear a conversation with Rossi and Trent and Joel talking about what they want the ski to do and the best way to get there. There are going to be many commonalities but I'd bet there are some nuanced differences.