You did not say, but if it says just "Vaquero" on the frame, it's merely a fixed-sight/smoothed top-strap version of the full sized, adjustable-sight New Model Blackhawk which has been produced essentially unchanged since 1973 (the Vaquero was built from the 1990s through 2005 or so, with occasional clean-up runs showing up). Otherwise, same basic gun except for the Vaquero's steel (vs aluminum) gripframe and ejector rod housing.
If it says "New Vaquero," made since 2006, it's part if the newer, slightly smaller mid-frame series which also includes adjustable sight 50th Anniversary .357 flattop and, most recently, .44 Special flattop. These are closely patterned after the (size of the) original Ruger flattops of the 50s as well as the famous Colt single action (SAA). Unlike the full-sized Vaquero and NM Blackhawk, the New Vaquero is not offered in .44 Mag. The mid-frame guns can shoot basically any .357, while "hot"/"Ruger Only" .45 loads are to be reserved for the larger frame guns. Contrary to popular myth, like the Colt and its clones, the mid-frame New Vaquero can handle "regular" .45 loads fine, not just powered-down "cowboy" loads.
The "odd" one in a sense, is a sort of hybrid: the 50th Anniversary .44 Mag Blackhawk (flattop), which marries the new smaller flattop gripframe with the "regular" (larger) NM Blackhawk cylinder frame.
The Bisley is a special longer (and differently shaped) gripframe/hammer combination favored by many especially shooting hotter loads--for better recoil control...or others just find them more comfortable to handle and shoot--available (generally)
in all the frame model/configurations above.
There are a myriad sub-variants, special caliber runs, but-if details, exceptions, etc., not discussed here, but these are the basic "modern" (recent decades) choices and differences. All modern-era (post '73) Rugers are "New Models" (NM)--characterized by the transfer bar mechanism allowing a "full six" loaded, versus the hammer-mounted firing pin single action models patterned after the Colt design, which continues today--which "requires" (highly recommends) just five (load one, skip one, load four).
Later edit: regarding finishes, the large ("regular"Blackhawk) frame Vaquero and, until 2009, New Vaqueros had a chemically applied "color-case hardening-look" finish on the frame. Many owners either didn't care for the look or had problems with rusting or at least wear-off, as of 2009 all fixed sight (NV) models are just blued--like their Blackhawk brethren--or of course stainless. Stainless large and mid-frame (flattop) Blackhawks generally have a duller or flatter, satin stainless finish versus the glossy stainless Vaqueros, differentiated presumably for the Vaqueros to look like the nickel Colts of yore, which they don't do a bad job of.
