I think Because its released for the first time
the result of him having senju DNA, whereas other hosts dont have nay special chakra.
maybe so6p sealed some of his chakra to kyuubi thats why naruto and kyuubi has strange markings in their body ???
what? ssj1 and ssj2 are the only semi somewhat looking physical appearances, ssj3 and ssj4 look nothing like any others..... smiley face?
haha while comparing to dbz is dumb and possibly banned? 3 is still damn similar. The only difference from 2 to ssj3 is the hair grows down to the ground. Your thinking of ssj4 and fusion ssj5
but when naruto was fighting pain his 8th tailed version was fleshso yeah its probably cause kurama can only give him a little bit of chakra