The most senior naval ranks, collectively called "flag ranks", include Vice Admirals, Rear Admirals and Commodores, have comparable seniority to Generals in the Army or Air Force. These ranks may have command of fleets, squadrons or task forces composed of multiple vessels.
The other commissioned ranks in modern navies include Captain, Commander, Lieutenant Commander and Lieutenant. These are roughly comparable seniority to the army ranks Colonel, Lieutenant Colonel, Major, Captain and Lieutenant.
Commissioned officers generally had military training at the University level.
Modern navies also employ various non-commissioned officers, petty officers and warrant officers — individuals who may be very skilled and experienced, but did not have military training at the University level.
Seamen are the most junior enlisted personnel in many modern navies, roughly equivalent to a private in modern armies.
An Office Holder on Wikispooks
Raymond Oliver. "Why is the Colonel called "kernal"? The origin of the ranks and rank insignia now used by the United States armed forces". McClellan Aviation Museum. Archived from the original on 2011-04-22. Retrieved 2011-04-22. Unknown parameter