Hey guys this is just my guess on the whole matter that got a lot of people confused; Sorry if this has already been pointed out by people. I may be wrong but here's my interpretation:
So before the Kyuubi went to "sleep", he gave Naruto the very last of his chakra telling him to use it wisely and all that shit. Looking back at the old fight, Naruto used the chakra from the nine tails cloak to form the first unique rasengan.
Then we take a look at Sasuke, who used a senjutsu enhanced Chidori which made it black.
Now coming back to this fight, Naruto's rasengan looked totally normal, but because he used the nine tails chakra to form it, I can assume that it is probably a a red color. And since the Kyubi probably has "better" or more intense chakra than Naruto, the Rasengan was also stronger.
As for Sasuke, since he didn't have the curse mark and I'm pretty sure didn't have any of the Sage's chakra left, he couldn't add senjutsu into his Chidori, so he just used Enton as an alternative.
So before the Kyuubi went to "sleep", he gave Naruto the very last of his chakra telling him to use it wisely and all that shit. Looking back at the old fight, Naruto used the chakra from the nine tails cloak to form the first unique rasengan.
You must be registered for see images
Then we take a look at Sasuke, who used a senjutsu enhanced Chidori which made it black.
You must be registered for see images
Now coming back to this fight, Naruto's rasengan looked totally normal, but because he used the nine tails chakra to form it, I can assume that it is probably a a red color. And since the Kyubi probably has "better" or more intense chakra than Naruto, the Rasengan was also stronger.
As for Sasuke, since he didn't have the curse mark and I'm pretty sure didn't have any of the Sage's chakra left, he couldn't add senjutsu into his Chidori, so he just used Enton as an alternative.