Working on some plausible mid-future spaceships:
That's a Torpedo Frigate up top and a Destroyer underneath. Each carries a few point-defense gauss cannons and the Destroyer mounts a pair of railguns. In order to power those big guns, it needs a reactor in addition to the main drive reactor, making it heavier and more expensive. The red things are radiators so the reactors and crew won't melt.
More to come.