Federal TRU 55gr BTHP is marketing. 'TRU' means Tactical Rifle Urban using a Sierra HPBT with milspec brass(thicker than regular brass), low flash powder and crimped in primers. Supposedly sold to LEO and "military agencies" only. Not necessarily a GameKing though.
The ammo you have likely is the same bullet though. Sierra doesn't make another 55 grain HPBT. Although they may be making a generic bullet specifically for Federal TRU ammo.
"...Federal Premium..." Regular commercial hunting ammo loaded with a GameKing. Also comes with a 55 grain Nosler BT.