[quote="xLilacVixenx"]I don't really see what this discussion is about anymore.[/size][/quote]
Well, as the original question about who Fluffy is, has pretty dang much been settled now for those who really truly care about the answer... I personally have tried to turn this into a general discussion about Fluffy. =D
Did you notice how the sequel's makers did pay attention to the fact that Fluffy had no 'paint' on its forehead when it was held up by Rafiki? They had Rafiki mark Kiara only after she had been presented. So they obviously had paid attention to the ending's cub and used all that they saw essential.
As the cub didn't have an identity whatsoever in the canon, its looks became unessential, too. And thus the sequel film's makers were able to redesign it without truly contradicting the canon.
Why they changed the design? Perhaps they thought it would be weird to have a girl who looks so much like Simba? But my best guess is that perhaps they just wanted the cub to have more personal looks? After all Kiara does look a bit peculiar for a lion cub. Her head's shape is weird. And then, perhaps they trusted that most fans would be interested enough to listen to the commentary track of the first film and thus find out that the original cub is genderless and nameless and that they aren't really contradicting the canon in story aspects.
Then there's a question why did they turn genderless Fluffy into a girl? A boy would've served the Romeo & Juliet story base the same. Simba and Nala would've just been Romeo's parents and Zira been Juliet's parents and Vitani could've been Juliet. But I guess they wanted a refreshing change for the main good guy character and chose it to be a princess with identity issues different from her father's. (: