Uniforming the primer pocket takes material out of the primer pocket so that each primer is seated to the same exact depth, flash hole deburring removes the burr from inside the case where the flash hole enters. Neither one are bad to do and can only help, but for the extra effort, turning a 1” rifle into a .998” rifle, won’t be worth it for most. In multiple rifles I have tested brass with primer pockets uniformed and flash holes deburred, against brass that was similarly prepped except for having nothing done to the primer pockets or flash holes. Those 3/8” rifles were still 3/8” rifles at the end of the day.
JTD