Same hull cvz-18 versus the cvx-18, though many cvz's came with a 305, whereas the CVX were mostly 350's. The CVZ-18 has a belly fuel tank which is different than a CVX-16/18. There should be two access plates, one for the sender, the other for the pickup. Spend some time inspecting these areas for aluminum corrosion and fuel smells/leaks if the floor is rotten, I'd recommend a poly tank replacement, so that's a cost to figure in. Both are fantastic models, the z being a bit more family oriented. Better storage, and an optional top exists to cover the bow(convertible). If you like to beach your Glastron, you rarely get your feet wet, you just walk out the bow. Funny really, I graduated from a 16SS to a Z cuz I had to have a V-8.