Question: why naruto bijuu mode is different?
Answer: When Naruto is in Level 2 bijuu mode you see the cloak of chakra, his hair, and the black markings all over his body make him look a lot like Rikudou Sennin did. Also the reason for Naruto's bijuu-related abilities being different from other jinchuurikis, it's because he does not possess ALL of Kurama inside him.