So we know there are two kinds of HVLP guns. the gravity feed paint on top version and the paint on the bottom (venturi) version. Now my paint on the bottom is a 1.8 tip and I need this to help shoot a bit thicker stuff. Whats the difference between these two guns? Do they both do the same thing? There has to be a reason for the different designs. Will some experienced painter out there explain it to me? I am painting a frame will it still lay down the same and the primer did with the paint on the top gun?