what is the difference between an officer and a non commissioned member
Non-commissioned officer A non-commissioned officer or noncommissioned officer (NCO, colloquially non-com or noncom) is a military officer who has not earned a commission.[1][2][3] Such is also called sub-officer in some countries. Non-commissioned officers, in the English-speaking world, usually obtain their position of authority by promotion through the enlisted ranks.[4] In contrast, commissioned officers hold higher ranks than NCOs, have more legal responsibilities, are paid more, and often have more non-military training such as a university diploma. Commissioned officers usually earn their commissions without having risen through the enlisted ranks. "Mustang" is a slang term in the United States Armed Forces used to refer to a commissioned officer who began his or her career as an enlisted service member.[citation needed]
Petty officer The modern petty officer dates back to the Age of Sail. Petty officers rank between naval officers (both commissioned and warrant) and most enlisted sailors. These were men with some claim to officer rank, sufficient to distinguish them from ordinary ratings, without raising them so high as the sea officers. Several were warrant officers, in the literal sense of being appointed by warrant, and like the warrant sea officers, their superiors, they were usually among the specialists of the ship's company.[1] The Oxford English Dictionary suggests that the title derives from the Anglo-Norman and Middle French "petit", meaning "of small size, small, little".[2]