Minato's version is superior, his versatility with the technique is greater and he created more variations with it. He preps his weapons with his jutsu formula before hand, which gives him the advantage over Tobirama who marks on the fly. Minato also created the like of the Hiraishin Dorai (Flying Thunder God: Guiding Thunder), which is a space time barrier than can pretty much redirect any projectile.
From the Fourth Databook:
1. Tobirama’s developed jutsu were later inherited by a disciple, a user whose name was rising. Namikaze Minato improved the mastery of “Hiraishin no jutsu”, and thus took the nickname “The Yellow Flash”. The excellent jutsu was refined according to the disciple, who evolved it together with the era.
2. Minato handles to perfection the "Hiraishin no jutsu" invented by the nindaime Hokage, Senju Tobirama.
3. Second Hokage producing a spacetime ninjutsu and the Fourth Hokage taking this technique and pushing it even higher.