The Ruger Vaquero is Ruger’s take on the Colt Peacemaker. It’s notable for having a more beefy frame in order to take more abuse (as with the Redhawk and GP100). The cylinder is also freed just by opening up the cylinder release, whereas the Colt Peacemaker required you to bring the hammer back to half cock (there is no such feature on the Vaquero).
The Vaquero is available in either a 4.75 or 5.5 inch barrel, and most commonly in either .357 Magnum or .45 Long Colt. An even beefier version called the Blackhawk is also available with raised target sights, but is likewise based on the Colt Peacemaker platform as well.