It's just a speculation

But if you want my idea, this is it:
- On this pic:
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Notice that Sasuke and Naruto ran towards Obito to create an opening in advance when Tobirama and Minato stayed backwards for the supposed mainpart
On this pic however we see Minato suddenly appearing(that happened after Tobirama appeared behind Obito):
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Remember that Naruto and Sasuke were far away from them(Minato and Tobirama) at that moment since they made the first step a while ago, but we see Minato suddenly appearing before them when not even an instant earlier he was discussing with Tobirama.
Tobirama appeared behind Obito because he marked him. But for Minato to be there that instantly, i thought first he used shunshin, but the sound effect around it makes me think he used Hiraishin instead
But here is the thing. Where is the marking where he teleported to. He only marked Tobirama an instant earlier and same Tobirama was behind Obito away from him, yet he managed to appear just before Naruto and Sasuke. So i believe the difference between Minato's lvl1 Hiraishin and Tobirama's is the radius where Minato is capable to teleport. I think Tobirama's marking only allows him to teleport near the marking in question. Minato's marking on the contrary can make him teleport around a certain radius. I think it's the reason why their markings are different. Minato probably extended the range of the jutsu
What made me confirm this further is this panel:
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Tobirama asks Minato if he can fly directly to Naruto, but how can he ask him something like this when he never marked Naruto? The only marking he has at that moment is on Tobirama(and vice-verse since they put marking on each other). And Minato replied that the only reason he couldn't was because of his chakra reserve, which means that if he indeed had more chakra, he could have teleported to Naruto, when Tobirama apparently couldn't since he asked if Minato can(the fact he asked him means himself couldn't).
Since both were in the same position(markings in the same position), i suppose then that what would have allowed Minato's hiraishin to teleport there when Tobirama couldn't is the radius i was talking about