Álvaro de Bazán and Hobart blur frigate and destroyer labels

The Álvaro de Bazán class gives Spain a capable Aegis-equipped air-warfare combatant despite its official frigate label. The related Australian Hobart class is larger and called a destroyer, though the difference is one of degree rather than a clean break in mission. Frigate and destroyer labels can still describe anti-submarine and anti-air orientations while both types retain substantial general-purpose capability. Shrinking fleet numbers then force both to perform cruising and presence work that once belonged to a separate cruiser category.