what's the difference between the army and the royal marines
Royal Marines The Corps of Royal Marines (RM) is the amphibious light infantry and one of the five fighting arms or branches of the Royal Navy.[2][3] The Royal Marines were formed in 1755 as the Royal Navy's infantry troops. However, the marines can trace their origins back to the formation of the English Army's "Duke of York and Albany's maritime regiment of Foot" at the grounds of the Honourable Artillery Company on 28 October 1664.[4]
Marine Security Guard A Marine Security Guard (MSG), also known as a Marine Embassy Guard, is a member of the Marine Corps Embassy Security Group[3][4] (formerly Marine Security Guard Battalion), a battalion-sized organization of U.S. Marines whose detachments provide security at American embassies, American consulates and other official United States Government offices such as the United States Mission to NATO in Brussels, Belgium. The Marine Security Guard was designated MOS 8151, this has changed to MOS 8156.