What is the difference between a NATO accredited COE and any other COE?

As per MC 0685, a NATO-accredited COE (also referred to as a “NATO COE”) is a COE that has been established by SACT, has received MC endorsement, and has received subsequent North Atlantic Council (NAC) approval. Only when these steps are complete can a COE be called a ‘NATO-accredited COE’. If NAC approval has not been granted, then it is not a NATO-accredited COE. Further, “Once accredited, the NAC may grant a COE international status under the Paris Protocol.”