More details of the Good Service Awards available can be viewed here. In summary:
Commissioner's Commendation - this can be used by Commissioners to recognise adult and youth members and non-members for their contribution to Scouting. This award carries no criteria and is worn in the same location on the uniform as other adult awards.
Chief Scout's Commendation for Good Service - the nominee should have a minimum of five years good service
The Award for Merit - the nominee should have a minimum of 12 years (exceptionally 10 years) outstanding service
Bar to the Award for Merit - the nominee must have been awarded The Award for Merit and completed five further years of outstanding service.
The Silver Acorn - the nominee should have a minimum of 20 years of specially distinguished service
Bar to Silver Acorn - the nominee must have been awarded The Silver Acorn and completed five further years of specially distinguished service
Silver Wolf - for service of the most exceptional nature, it is not normally considered before The Silver Acorn has been presented