Vitani dosen't really have a tuft. It's a mop: a thick mass
of disordered hair.

Yeah, Simba was younger than Kovu, as Zeldaholic said. And
too, male cubs start to lose the black around their ear when
they start growing up. Kovu was a lot older than cub Simba,
if you get what I'm saying.

Not so sure on Vitani.

Simba did have a tuff when he was a cub. It just wasn't
shown as much.

well when Simba was younge he...had a little tuft and
Vitani.....is uh

I think it's because Simba was younger than Kovu, Kopa and
Vitani when he was shown as a cub. Notice that Kovu was
already starting to lose the black around his ear.