the name of the model of ruger is on the frame
The old model Vaquero just says Ruger Vaquero on the frame, it's a larger gun, heavier, bigger cylinder, beefier, over 700,000 made since about 1993 or so. Usually has wood or fake ivory grip panels. Is availabel in blued and stainless, and comes in several calibers and barrel lengths.
The New Vaquero was just released this year, says New Vaquero on the frame, is a smaller frame, cylinder and is lighter, comes with black hard rubber panels. Is available in blued and stainless, in .357 mag and .45 Colt only.
The New Vaquero is the same size grip and frame as a Colt, and all the clones. The old (or regular) Vaquero is larger and heavier by a bit.
Good luck choosing, there's a PLETHORA of single actions out there.