The Civil Authority is a militarized police force tasked with keeping the streets clean of undesirables. The CA i restricted to cities and are usually dealing with rebellious behavior, or just general undesirables. The CA employs a little over 5 million officers which are distributed throughout the 4 planets under Sivean Control. Most of which being on the Sivean Home world, also named Sivean. CA officers who are in smaller cities are usually more abusive when it comes to their power. However many efforts have been made to reduce this problem. Such as executing officers publicly who have been known to constantly abuse their authority.
The Galactic Authority is the armed forces of Sivean. GA are rarely deployed in cities and usually keep to the thick jungles of Sivean or safekeeping the planets under Sivean control. The GA value quality over quantity making it much smaller than the CA. Consisting of about 1.5 million troops, all of which are trained to be able to fight in most conditions found on the planets under Sivean control. The few times GA is in a city, it's usually to crumble a medium to large scale rebellion.
The GA is not just on planets however, there is also a fleet of ships to patrolling the stars. Ships usually stay out of the atmosphere on planets. Tho on rare occasions they are needed to rain fire down on pesky rebels.