We have a total of 20 attainable ranks for each branch. While they are not all necessarily used at any moment in time, each rank has its purpose.
Senior Officer/Field-grade (O-4 through O-6)
In the Navy, Senior Officers are in charge of larger overarching divisions such as aviation wings, and certain ships. Field-grade Officers are generally the leaders of the 28th MEU and its battallions.
Junior Officer/Company-grade (O-1 through O-3)
In the Navy, Junior Officers are in charge of a Staff Corps, aviation squaqdrons, or are simply pilots, and can also lead SWCC teams. Company-grade Officers (for the Marines) are the leaders of Companies, Platoons, Aviation Squadrons, and can lead MARSOC teams.
Chief Petty Officers/Staff Non-Commissioned Officers (E-5/E-6 through E-9)
In general, the CPOs and SNCOs of the Navy and Marine Corps, respectively, have the same duties, just translated to their respective divisions. For example, both SNCOs and CPOs are the people between the regular Enlisted and NCO population and the officers, putting them in a position right in the middle of the Chain-of-Command. Furthermore, both positions generally call for 'morale-boosting' personalities.
Petty Officers/Non-Commissioned Officers (E-4 through E-5/E-6)
While the Navy does not have Infantry squads, a Petty Officer may lead a certain part of a crew, or lead a SWCC element. NCOs are usually in charge of a squad, fireteam, or section.
Apprentices/Junior Enlisted (E-1 through E-3)
For every branch of the United States' Armed Forces, the ranks of E-1 through E-3 are the starting ranks and make up the manpower of the entire military. These personnel can take a broad range of positions, although they are usually not in any kind of leadership position.
|Senior Officer Ranks|
|Junior Officer Ranks|
|O-2||LTJG||Lieutenant (Junior Grade)|
|Warrant Officer Ranks|
|W-5||CWO-5||Chief Warrant Officer 5|
|W-4||CWO-4||Chief Warrant Officer 4|
|W-3||CWO-3||Chief Warrant Officer 3|
|W-2||CWO-2||Chief Warrant Officer 2|
|W-1||WO-1||Warrant Officer 1|
|Chief Petty Officer Ranks|
|E-9*||CMDCM||Command Master Chief Petty Officer|
|E-9||MCPO||Master Chief Petty Officer|
|E-8||SCPO||Senior Chief Petty Officer|
|E-7||CPO||Chief Petty Officer|
|Petty Officer Ranks|
|E-6||PO1||Petty Officer First Class|
|E-5||PO2||Petty Officer Second Class|
|E-4||PO3||Petty Officer Third Class|
|Field-grade Officer Ranks|
|Company-grade Officer Ranks|
|Warrant Officer Ranks|
|W-5||CWO5||Chief Warrant Officer-5|
|W-4||CWO4||Chief Warrant Officer-4|
|W-3||CWO3||Chief Warrant Officer-3|
|W-2||CWO2||Chief Warrant Officer-2|
|Staff Non-Commissioned Officer Ranks|
|E-9||MGySgt||Master Gunnery Sergeant|
|Non-Commissioned Officer Ranks|
|Junior Enlisted Ranks|
|E-2||PFC||Private First Class|