• In canon, Itachi is a pacifist and prevents any kind of fight as long as he can. || In RTN, he doesn’t mind fighting at all, and is always up to the challenge to the point of maybe provoking a battle or intimidating the opponent into doing so (As it was seen in the movie when he activated his Sharingan against Obito/Tobi).
• His Sharingan is always active or at least, most of the time. Has used the Mangekyo several times as well, leading to blindness. || He only activates it when necessary, and hasn’t used his Mangekyo much at all so he’s not blind yet.
• He has an incurable condition that leads to his eventual death, also affecting his stamina. || He’s healthy, and has more stamina.
• Itachi is quiet, reserved and keeps everything to himself. || He’s more expressive.
• Has no interest in romance or sexual situations. Completely immune to flirts or other forms of seduction. || Itachi is a smooth talker, flirtatious and seductive though in a very disguised way, unlike his brother Sasuke.
• He’s selfless when it comes to the village and those he cares for. || Is more selfish and somewhat possessive with those he cares for.
• Is a member of the Akatsuki. || Is the leader.
Contrasting Canon and RTN Itachi