What were some of the ways the byzantine empire changed during justinians reign

One of the achievements Justinian is most famous for was his overhaul of the Roman legal code. His revisions of the law included greater protection for women, including trafficking protection, tougher penalties for abuse, and the return of a woman's dowry is she is widowed.

Militarily, Justinian managed to conquer a great deal of the territory that the Western Roman Empire had lost over the years. He considered it his Christian duty to restore the old borders of the empire, and came a long toward that goal, including conquests in Italy, North Africa, and winning claims from the Sassanid Empire.

Another change that was made was a more strict interpretation of legitimate Christian doctrine, and a harder line on less mainstream Christian sects, such as Monophysitism. Justinian was heavily involved in the regulation of religious life in the empire, much like his hyper-involvement in the other areas of his administration. 

Justinian is also famous for his many construction projects. He was passionate about architecture and it was during his reign that the famous Hagia Sophia was completed.