I don't believe so, Mufasa's mane is more 'thick' and 'holds up' while Simba's mane is more 'wide' and 'goes down'. Mufasa's features resemble more of an 'older' age. But Simba's appear more 'soft' and in their prime.
Even in SP, he still holds a bit of 'youth'.
Ha, I like that comparison.
It makes sense too. Mufasa has that 'old but powerful' feel to me. While Simba has that 'young or hip-hop" feel to me. I mean just look at that grin. 
(Mufasa still looks like a handsome and great King though.) And about Simba.
Well, you have to understand. He was just a cub when his dad died. But he also thought HE was the reason for his death. Simba was traumatized, he probably felt it for a long time. When he was 'adopted' by Timon and Pumba. They teach him that bad things happen and there's nothing they can do about it. He had Hakuna Matata. Something that he did need after what he's suffered. Though, that is true. He did forget everything he was taught by his father. BUT he did soon realize what truly mattered, his true destiny..
Mufasa however was most likely brought up as the 'golden boy' who could do no wrong, his father was probably obsessed with grooming him into the greatest heir of his bloodline. He was probably taught about 'strength' and 'courage'. But he may of also been too 'boastful and proud' as a young lion. Much like his son as a cub. But Scar was the overlooked one. Seen as garbage. Neglected by his father. But he still had his mother who loved him. But as he grew older, he became more 'jealous' of his brother and felt like an 'outsider'. Mufasa also might of been the one to give his brother that scar in the first place. And the hyenas probably manipulated him and turned him evil.
Mufasa never had 'Hakuna Matata'. But he DID have wisdom and guidance from his father and possibly Rafiki.
But he would of made mistakes in his past, just like Simba. But as we see in the film, he is very wise and a caring dad. We can see though in SP, Simba had never let go of his hate for his uncle, but that was probably because of Zira and the outsiders who reminded Simba of his uncle. (And believing that he was a murderer didn't help either.) He was paranoid about Kovu murdering him, he saw him as what Scar or Zira had intended him to be. He even suffered nightmares about Mufasa's death. But in the end he let go of his hate and finally saw what his daughter meant. That they are one. 
