Depends on the BFR.
A BFR is a "Ball Family Reserve" special run of what ever model they want to make a custom limited run of.
It can be an SR5 with a different paint job, it can be a full single-painted neck and body with gold hardware, or it can be an all-rosewood neck you can order on any model. These are examples of what they're done in the past.
Every year they seem to do at least one BFR, sometimes two or three. So it can be just a color, or it can be different wood or electronics package.
But back to the sound question; The original Leo/preEB StingRays were 2 band eq, string thru, mute bridges, slab bodies. Yes the 2 band is different form the 3 band, they're voiced differently.
For a couple of decades you could order a 2 band eq on a standard StingRay, but now that the current StingRay Special replaced the old standard StingRay, the 2 band then only came on the Classic (which is still currently unavailable).
Now the Classis is a beautiful bass, I have one ( have had many), but they have a few modern features that still separate it from my original '78.... they're still very different.