Free Planets Alliance officers in Legend of the Galactic Heroes can be distinguished primarily by the rank insignia on the collars of their uniforms.  There are three major branches of the Alliance Armed forces: The Navy (Free Planets Space Fleet), the Marines (for example, the Rosen Ritter), and the Alliance Air Corps. Conjecture also suggests there is a Free Planets Alliance land Army.

Ranks Table

Historical Navy	Historical Army	Alliance Army	Alliance Navy	Alliance Marines	Alliance Air Corps	Rank Insignia	Japanese Kanji
Private	Private	Private	Spaceman	Private	Airman
Private First Class	Private First Class	Private First Class	Able Spaceman	Corporal	Lead Airman
Corporal	Corporal	Corporal	Lead Spaceman	Lance Corporal	Corporal
Petty Officer	Sergeant	Sergeant	Petty Officer	Sergeant	Sergeant
Chief Petty Officer	Staff Sergeant	Staff Sergeant	Chief Petty Officer	Staff Sergeant	Flight Sergeant
Master Petty Officer	Master Sergeant	Master Sergeant	Master Petty Officer	Master Sergeant	Senior Flight Sergeant
(Midshipman)	Cadet Lieutanent	Sub-Lieutenant	Ensign	Officer Candidate	Warrant Officer
(Sub-Lieutenant)	Sub Lieutanent	2nd Lieutenant	Sub-Lieutenant	2nd Lieutenant	2nd Lieutenant
(Lieutenant Junior Grade)	(2nd Lieutenant)	1st Lieutenant	Lieutenant, Junior Grade	1st Lieutenant	1st Lieutenant
(Lieutenant)	(Lieutenant)	Captain	Lieutenant	Captain	Captain
(Lieutenant Commander)	Major	Major	Lieutenant Commander	Major	Major
(Commander)	(Lieutenant Colonel)	Lieutenant Colonel	Commander	Lieutenant Colonel	Lieutenant Colonel
(Captain)	(Colonel)	Colonel	Captain	Colonel	Colonel
(Commodore)	(Brigadier)	Brigadier General	Commodore	Brigadier General	Brigadier General
(Rear-Admiral)	(Major General)	Major General	Rear Admiral	Major General	Major General
(Vice Admiral)	(Lieutenant General)	Lieutenant General	Vice Admiral	Lieutenant General	Lieutenant General
Admiral	General	General	Admiral	General	General
Fleet Admiral	Field Marshal	Field Marshal	Fleet Admiral	n/a	General of the Air Corps

Notes

• The Free Planets Alliance rank system is not directly based on any particular country's rank system. The closest match that exists is the Royal Air Force (RAF). This seems to be the case regardless of whether the Free Planets Alliance forces are fleet-based, air-based, or land-based. 
• Most of the current translations of the series seem to try to fit the Free Planets Alliance ranking system into the American or Japanese rank systems, so what you may have seen in the fansubs might be different from what you see here.

fparanks.htm / April 13, 2000