Battleships: the latest designs were the ‘dreadnoughts’, a generic term taken from Britain’s revolutionary ship of the same name. Their armament was focused on a few heavy guns in four or five large turrets. Secondary batteries of lighter guns were also carried. However both Britain and Germany still had older designs of battleships called ‘pre-dreadnoughts’. These tended to carry a wider range of guns of different sizes, with only one or two main gun turrets. They were slower and weaker than the new battleships. The Battle of Tsushima in 1904 (Russo-Japanese War) was fought with pre-dreadnoughts.
Battlecruisers: created by Britain’s Admiral ‘Jackie’ Fisher, these battleships sized but lightly armored vessels carried heavy guns and were designed to to quickly reach distant waters to protect British merchant ships or to destroy enemy trade. They could also scout for the battlefleet. They were not intended for a slugging match with heavily armed opposition. Germany built her own battle cruisers in response, but her versions were much better protected.
Battleships and Battlecruisers are often referred to as Capital Ships.
Cruisers: a term covering a range of middle-sized warships intended for various roles.
Light Crusers: were designed as scouts for the battlefleets, but could also launch torpedo attacks.
Armored Crusiers: were more heavily armed and protected ships. Some were used for commerce raiding but others could stand up to pre-dreadnought battleships, Such as the Tyne built Japanese armored cruisers at Tushima.
Destroyers: small and fast warships originally designed to protect battleships from enemy torpedo boats, hence their original designation as ‘torpedo boat destroyers’. This was abbreviated to ‘destroyer’ as the ships as the ships also took on the role of attacking with torpedeos. They operated in flotillas led by by light cruisers or purpose built large destroyers, known as Flotilla Leaders. The crews had very little protection.