In previous times that approach was executed down to piece-parts level (resistors, switches etc.)
whereas nowadays it is tried to reduce cost by usage of "CAM (Commercial, Avionics, Military) equipment" for non-safety relevant units.
Qualification is the formal proof that the design meets all requirements of the specification and the parameters agreed in the Interface Control Documents (ICD) requirements with adequate margin, including tolerances due to manufacturing imperfections, wear-out within specified life-time, faults, etc.
Acceptance is the formal proof that the product identified is free of workmanship defects and meets preset performance requirements with adequate margin.
The end of the acceptance process is the approval signature of the customer on the CoA, or QDD, agreeing that all the requirements are met by the product to be delivered under the terms of a contract.