It is said the Kol (and maybe the Corsev) were the only intentionally built warships. The other 4 caps were all civilian vessels, likely trade ships or freighters.
IIRC, it's that the Kol was merely the first ship intentionally built as a warship- at least for a very long time. I think it's fairly obvious that some vessels were pretty explicitly warships; things like the Garda and Javelis in particular- as well as the Ogrov- come to mind.
The Dunov and Akkan are explicitly mentioned as civilian shipping/personnel transport craft that were converted to warships; the Marza is a large-scale astronomical body demolitions/mining platform [IIRC, it's called a "planetoid wrecking and recovery" something-or-other]. The Sova is mentioned as being a long-serving anti-pirate vessel.
As the above poster mentioned, the Corsev was probably a tanker. Hosikos are mentioned as being converted to the purpose of war as well; Percherons are also likely converted hulls, as are, IMO, Kodiaks. The Raloz is likely also a converted ship in terms of concept- it might be that at one point such ships were used commonly for orbital structure building. The Neruda envoy cruiser is almost certainly a converted hull- or at least a late-war program for ships intended specifically for diplomatic purposes.
The Krosov, IIRC, is mentioned as being a converted freighter of some variety. Protevs are pretty obviously "civilian with piddly guns bolted on", as is the Arcova. The Cobalt I'm not so sure of; it just seems too purpose-built as a warship, and doesn't appear to really have the internal volume for cargo carriage in useful [IE, economically sensible/competitive] amounts, but I could very well be wrong. On top of that, I'd say that the corvette hulls, and pretty obviously the Titans, are both purpose-built warships.
At the very least, that's my take on it.
