To add to Metwrench's explanation, the inboard tabs are the servo tabs, each side is connected to the same side control column, the columns being connected under the cockpit floor by spring-loaded disconnect system, in case of pitch system jam on one side.
60 lbs force will break out the disconnect, then you discover which side was jammed and which pilot still has pitch control.
Each servo tab circuit has a "blow back spring" to limit the tab's authority according to airspeed.
Trim tabs are the outboard sections, and are controlled conventionally by cables, rods and screw jacks. Inputs are the thumb operated trim switches, manual trim wheels, and the autopilot.
Regards - Musang