: Well, the Rapid Conversion, the first Covie ship to arrive at Harvest, was
: only listed as a "cruiser." So, maybe it was a CRS class, but
: the UNSC labelled it a "cruiser" because even though it's small,
: it likely has a ton of firepower as well as energy shields, making it an
: even match for the much larger UNSC cruisers. And assuming the ship that
: the frigates Vostok & Arabia and destroyer Heracles fought was the
: Rapid Conversion, a cruiser designation based on firepower may have been
: warranted given that the "fight" was a 14-second curb-stomp
: battle.

Or it's all just a bit of a muck up. :P
Human convention is based on tonnage and role, not firepower.
That is the only difference between the different classes of aircraft carriers.
Though even a light aircraft carrier such as the Invincible-class (which were termed 'Through-Deck Cruisers' after 'aircraft carrier became a dirty word in UK politics) are significantly higher tonnage than other ships.
The heaviest 'cruisers' in the world are the Russian aircraft carriers.
Designated in Russia as "Heavy Aircraft Carrying Cruisers"