To this commenter, the Navy’s Officer rank structure
Navy, Coasties:
O-10:Fleet Admiral
O-10:Admiral
O-9: Vice-Admiral
O-8: Rear Admiral
O-7: Rear Admiral Lower Half
O-6: Captain
O-5: Commander (Full Bird)
O-4: Lieutenant Commander
O-3: Lieutenant
O-2: Lieutenant Junior Grade
O-1: Ensign
Was more straightforward and easy to remember than the Army’s:
Army, Air Force, Marines:
O-11:General of the Army
O-10:General
O-9: Lieutenant General
O-8: Major General
O-7: Brigadier General
O-6: Colonel (Full Bird)
O-5: Lieutenant Colonel
O-4: Major
O-3: Captain
O-2: 1st Lieutenant
O-1: 2nd Lieutenant
and, the fact that full birds in the Navy were of lower rank than full birds in the Army was just overall confusing.
The Russians seem to have only four flag officer ranks, at least in the Army, and not five flag officer ranks as in the U.S. Army and the U.S. Navy.
Typo in your post, Fleet Admiral would be O-11, not O-10. Also, the Navy and Coast Guard do not use the term “Full Bird”, since there is no confusion between O-5 (Commander) and O-6 (Captain). The Army, Air Force, Marine Corps, Space Force have O-5 (Lieutenant Colonel) silver oak leaves and O-6 (Colonel) silver eagle, so the term “Full Bird” comes from the actual O-6 Colonel rank having the eagle insignia, not the oak leaves of the O-5 Lieutenant Colonel though they both share the conversational title of “Colonel”.