Warship designation

[uk 75]

Back in the 60s as a kid reading Janes Fighting ships I remember being puzzled by the fact that navies had different ideas of what to call a ship. The US Navy were calling its big missile ships frigates. The Royal Navy had destroyers which were nearly as big as old light cruisers. But its future frigates and destroyers in the 70s were a similar size.
Today with the US Zumwalt being cruiser size and talk of the Aegis cruisers (the CG47s started life as Spruance DDG47s) being replaced by destroyers reminds me that I am as baffled by these terms as I was at 12.

 

[Hood]

When gun-armed ships went out of vogue there was less sense of what constituted a classification based on firepower and a shift towards ratings on capabilities. Generally these have merged over time.
I always thought the Russian/Soviet classifications made more sense in being more descriptive of the actual role.