Ah, words don't you love them. Ship classes change depending on setting. Take the Star Wars 'Star Destroyer' a dreadnought if ever I saw one
. So really what they mean is up to you.
Historically the various terms have changed their meanings over time, with one era's Frigate is another era's Destroyer or in another a Cruiser. For example the term frigate had died out by the late 19th century and was reinvented post WW2 to describe a WW2 style destroyer while the term destroyer would more closely match a WW2 cruiser.
That being said I think there is some consensus, here is my take
Corvette - light and cheap
escort vessel to guard convoys not expected to met enemy military vessels
Frigate - Heavier escort vessel rarely expected to be in a full battle (could also refer to a specialized escort vessel AAW or ASW for example)
Destroyer - Very heavy escort vessel used to escort battle line ships in battle (a general escort vessel if frigates are specialists)
Cruiser (general) General workhorse (historically tended to operate far from home base. A sailing era frigate)
--Light Cruiser - lightly armed/armoured vessel (most often found in foreign stations)
--Heavy Cruiser - more heavily armed vessel (capable of being used as battle line substitute)
Battle Cruiser - lightly armoured battleship
Battleship - the standard battle line ship able to both take and give out heavy damage
Dreadnought - A more capable battleship (historically late era battleships)
Monitor- A heavily armed ship which has little or no maneuverability/speed. (Historically used for shore bombardment)
Of course everybody will have their own take on this and a perfectly reasonable justification for it.