The Vaquero is a bit simpler, with less controls and features VS the Bandido II. But the Vaquero is also a bit deeper, since it features the "H.O.T." circuitry Tesoro uses on some newer machines.
The biggest difference is that the Bandido II has a Non-Motion All Metal mode, used for pinpointing. Also the Bandido II can switch between All Metal mode and Disc with the flip of a toggle switch.
The Vaquero Pinpoint button puts the machine in All Metal temporarily, but its "motion" All Metal with auto retune so you have to keep the coil moving. To put the Vaquero in All Metal to use it for hunting in that mode, you have to rotate your Disc knob towards iron until it clicks into All Metal. Not easy to switch between Disc and AM on the fly.
The Vaquero has a low pitch tone, the Bandido II has a high pitch tone.
The Bandido II has a "real" pinpoint feature, like most modern digital detectors with screens.
The Vaq uses 4 pin coils, the Bandido II uses 5 pin coils.
The Vaq is more powerful, but not by a huge amount.
Both are very easy to use, but the Vaq is a little simpler.
If the Bandido II sounds perfect for you, but you can't find a nice used one (which is likely, they were discontinued years ago and people tend to hang on to them) buy yourself a new Outlaw. It's basically an updated Bandido II with a little different control for the Retune and All Metal modes.