Battlecruiser labels conceal different combat roles

The early two-word 'battle cruiser' is treated as a cruiser for scouting and economic warfare. The later one-word battlecruiser is intended to fight heavier opponents. Fast battleships and battleships sit farther along the same spectrum, so speed alone does not make every fast capital ship interchangeable. An armour metaphor shows the distinction as growing coverage: first a shield and helmet, then a breastplate and leg protection, and finally near-full or full plate. British and German ships under the same broad label could therefore have different tactical roles and survivability.