Two similarly named organizations, but with drastically different doctrines, capabilities, equipment and missions. So, let us say that, by the will of ROB, a section of Royal Marines will be facing a squad of United States Marines in a firefight. There shall be three scenarios we shall consider: A: A firefight in a built-up/urban setting B: A firefight in a temperate woodland/jungle setting C: A firefight in an open grassland/desert setting. Both sections are dismounted, so no vehicle support, just section-level equipment and tactics. We shall assume that both the Royal Marine troop and the US Marine squad are made up of soldiers about equivalant in competency for their different missions, and led competently. So, in an advance to contact in the three settings I named, who would win?