AB763 2 channel vs AB&63 Two Channel Twin

[separateness]

AB763 2 channel vs AB&63 Two Channel Twin
Both of these are listed on the turret board information page,  what is the difference between them?  Clicking on the circuit name links both to the same page.

Apologies if this is a stupid or misplaced question, but I have searched in earnest for the answer before asking.  Thank you.

[HotBluePlates]

AB763 2 Channel is for an amp with 2x output tubes (Deluxe Reverb, Super Reverb, etc). The AB763 2 Channel Twin board is for the Twin Reverb, which has 4x output tubes.

The board is a bit longer with extra turrets on the Twin version, for screen and current-sense resistors for the two extra output tubes.

[EL34]

What HotBluePlates said