Ditto. The Vaquero is built like an M1A1 tank -- big, tough and heavy. If you have big hands, you may like it a lot. It is available in .44 Magnum chambering. You can shoot +P loads our of the .45 Colt versions that will put a serious hurt on just about anything.
The New Vaquero is smaller -- about the size of the Colt Single Action Army. It is available in .357 and .45 Colt only, and the .45 Colt version can NOT safely be used with +P loads. If you try to use loads that your loading manual says are for "Rugers Only", you may well blow up your gun and your hand. The New Vaquero cylinders just don't have enough metal to contain those pressures safely. For that reason, Ruger will likely never produce a .44 Magnum version of the New Vaquero. It may someday make them in .44 Special (I'm hoping and praying), but for .44 Mag you'll need to stick with one of the big boys.
The New Vaquero also has a new indexing pawl that lines the chambers up with the loading gate. That makes it quicker and easier to load. For years, cowboy action shooters have been installing aftermarket reverse indexing pawls on Vaqueros to make them load and unload easier, and now Ruger corrected the problem with the New Vaquero.
Finally, the New Vaquero has a reshaped hammer that some feel is easier to cock, especially one handed.
In the final analysis, the New Vaquero is the clear choice for cowboy action shooting, and for anyone who prefers a smaller and lighter revolver. The original Vaquero is for hunting and heavy loads, and for anyone who prefers a larger and heavier revolver.