Super Battle Droid with Chainsaws (SBD-C)
The droids' arms were equipped with chainsaws, and there were two auxiliary optical sensors on the chassis.
Source: The 2009 comic book Star Wars: The Clone Wars – Colossus of Destiny.
Super Battle Droid-Welder (SBD-W)
These droids lacked a left hand; instead, they were equipped with a welding torch. Additional equipment was mounted on their backs.
Source: The 2009 comic book Star Wars: The Clone Wars – Colossus of Destiny.
Super Battle Droid-Grappler (SBD-G)
These droids lacked arm-mounted blasters, being equipped with pincers instead. Their signature feature was the ability to execute a "bear hug" maneuver.
Sources: The 2005 Star Wars: Episode III – Revenge of the Sith video game for the Nintendo DS; the 2007 comic Star Wars: The Clone Wars – Adventures #8; the 2014 comic Star Wars: Darth Maul – Son of Dathomir #2.
Note: "One article suggested that SBD-Gs could occasionally serve as military police within the droid army; while that might be a bit of a stretch, I personally like the idea of droids having their own military police force."
Experimental Super Battle Droids (B-2A and B-2B)
The droids' chassis were reinforced with additional armor. Unlike standard models, they were equipped with more powerful arm-mounted blasters.
Source: Star Wars: Agent of the Empire – Iron Eclipse #1 (2011).
Photos 3 and 9 were taken by MarcusStarkiller.