The CDS focuses on military operations and strategy while the Permanent Under Secretary's remit concerns administrative and financial policy.

From the creation of the post until 1997, the Chief of the Defence Staff was appointed to the highest rank in the respective branch of the British armed forces to which he belonged, being an admiral of the Fleet, a field marshal or marshal of the Royal Air Force, (NATO rank grade OF-10).

However, during the 2010s Guthrie, Boyce, Walker and Stirrup were honorarily promoted to their respective services' senior ranks, sometime after they had each stepped down as CDS.

However, in 2016, a Royal Marine officer Gordon Messenger was promoted to the rank of general and appointed as Vice-Chief of the Defence Staff.

Customarily, former Chiefs of Defence Staff receive a life peerage on retirement,[b] sitting in the House of Lords as non-political crossbench peers.