Titan has always been a private military weapons manufacturer/contractor – providing both ships, weapons, men and services to any colonies requiring it. TDS found profit in supplying military ships and even military personnel to various colonies at an early point during its lifetime.
USR build its ship construction on a backbone of exploration and research. It grew from profits made exploring the galaxy and finding habitable worlds using self-sufficient ships designed for long distance travel. Eventually, the ships were adapted for military use.
Zarek was built upon a highly successful mining and construction corporation. They are specialists in zero-g construction and are responsible for building mining platforms, ship construction platforms and space stations.
All ships in Fractured Space are made by one manufacturer or another – and the difference isn’t purely cosmetic.