What is the difference between component service and inspection?
Servicing is lubrication or replenishment as required for a component to continue in service - greasing, adding oil etc.  Inspection is verification that condition of a component is acceptable, either visually, or using an enhancement method like Xray, ultrasonic, or various non-destructive test methods.

Overhaul/Restoration is disassembly, inspection and replacement of internal parts to bring the unit to some minimum dimensional/performance standard.   

The term Restoration is generally associated with MSG-3 based maintenance programs and is something like overhaul but often is restricted to specific components identified in endurance testing, or even just something like a grease charge that requires disassembly to remove/replace, again based on endurance testing. 

A restoration doesn't "zero time" a unit; it's more of a mid-life refresh.  MSG-3 based parts can be run forever theoretically, because the whole idea is you run the component until periodic functional testing in the field detects a performance degradation, but parts usually also have a structural life limit imposed on a root component like a housing, based on endurance/fatigue testing.  Once the root component reaches its life limit, the part is scrap.  That clock does not get reset by rebuilding the unit.