When trying to build a world, one has to strive to provide diversity. There is not single factory they produces every ship in existence. There is no planet where everyone wears hats. Competing factions can't completely dominate one another in either technology or industrial output alone. Usually its a game of rock/paper/scissors.
Different designs for ships, even with the same underlying technology, have different strengths and weaknesses that an opposing side would build ships to exploit.
In the world of Iliad-07, there are two major superpowers, and a lot of territorial factions. While we don't see much of the competition in our story's setting 20 light years away, details about the design doctrines of both sides will flavor the design of the Arthur C. Clarke.
The doctrines of ISTO and the Krasnovian Empire are flavored by history, experience, and the designs of the other factions.
The Krasnovian Empire is I imagine as a fusion of German and Soviet technology. They are generally the first with the worst. Their vessels always live on the cutting edge of performance. In all matters they feel they must stay ahead of their rivals. Their propulsion systems out-fly everyone else. Their weapons out-shoot everyone else. Their shields out-block everyone else.
The problem is getting one ship that can have the best of all three of those disciplines is impossible. So their answer would be to have a multitude of specialist vehicles. As their shipyards and factories are consolidated on Luna, they can afford spacious facilities with a multitude of dedicated assembly lines. Their proximity to Earth means that access to specialized trades is ubiquitous.
Where performance isn't critical, they fall back on standardized components that are made to be rode hard and put away wet. What those components may lack in quality, they make up for in quantity. Many systems have expendable components, those used parts either cast off into space or stowed for recycling/disposal back at port.
Krasnovian vessels are designed to go out, do their mission, and come back to a home facility for maintenance and overhaul. The Krasnovian logistics network is concentrated on a few key ports around the Solar system (Luna, the Jovian Moons, and their deep space logistics base in the Oort cloud.) Any long duration mission for Krasnovians generally involves lugging along a mobile base.
The balance is that Krasnovian vessels are not very field serviceable. When you run into trouble with a system, you kick in a backup unit and limp your way back home to port (or be towed in.) Crews operate the vessel, they don't maintain the vessel.
The International Space Treaty Organization (ISTO) is the "also ran" in the space race. The Kransovian Empire holds all of the strategically useful areas of the Solar System. Planets and satellites that can support large settlements and dedicated port facilities. ISTO has had to content itself with smaller bodies that are spread around the Solar system.
While the Krasnovian Navy is a budgeting priority, ISTO generally have to subsidize their capital ship costs by employing dual use Commercial/Naval vessels. Capital ships are civilian designs that are simply reconfigured with weapons pods instead of cargo bays.
ISTO does enjoy some dedicated military vessels, but only the size of frigates and below. These vessels have to compromise performance for endurance. This makes them more resilient to battle damage than a comparable Krasnovian design, at the cost of added personnel, greater mass, and more "waste" in terms of hallways to access spaces, isolation doors, etc.
ISTO operational tempo means that all of their vessels have to be designed to be operated for long periods of time without access to port facilities. They also have to minimize the number of expendable parts. Larger vessels (both Civilian and Naval) even grow their own food. This means that a great deal of internal volume on an ISTO capital ships is devoted to fabrication and logistics. With the requisite increase in the number of specialist personnel to operate those facilities.
These needs basically drive ISTO to build multi-role vessels. While the Krasnovians would deploy a dedicated patrol craft, reconnaissance craft, and search-and-rescue craft, an ISTO frigate performs all of those jobs at once. Krasnovians have dedicated intercepters and torpodo attack ships. ISTO has one class of fighter, with its role determined by the weapons loaded before launch. The ISTO navy has no cruiser, destroyers, or battleships. What they do have is a class of mega-vessels which are essentially mobile fleet facilities that contain squadrons fighters and a small fleet of frigates while sporting enough stand-off weaponry to destroy any attacking capital ships.
There has never been a full scale force-on-force engagement between the Krasnovian navy and the ISTO defense forces. Depending on the scenario, either side could prevail depending on what objectives they have to meet, how far from base they have to operate, and for how long.
Tactically, the Krasnovian Naval vessels have better performance. Their vessels are mass produced, and because each is focused on a single task, crew training is minimal. However, that performance comes at the price of a dependence on returning to base for service and replacement of expendable components. They can absorb losses, and provided lines of supply are maintained, win any battle of military attrition. Their maintenance doctrine keeps their most skilled staff out of the line of fire.
Strategically, ISTO vessels can operate in areas that the Krasnovian navy would find untenable. While ISTO vessels are less capable at specific roles, they can perform all of the roles of a modern navy with fewer vessels. An ISTO task force, based around a swarm carrier, could control any chosen region of space, almost indefinitely. However, swarm carriers cannot be mass produced. And while frigates are mass produced they are much more expensive per unit than a Krasnovian patrol craft, recon ship, or torpedo attach ship. The loss of one vessel represents a loss of not only the tactical operations crew, but the engineering and support crew.
There are a few other factions in the Solar system. But all of them are mainly focused on point defense or raiding.