The difference is that itachi is more tragic in the sense that when he does initially die, he dies with all the other characters still thinking he's a cold-blooded, genocidal killer. It's not until after he's dead that you learn how he gave his whole life away, swallowed his love for his family, as tobi said "wept tears of blood and slaughtered his brethren" and took all the insults in complete silence despite the pain and guilt, for close to a decade.
Jiraya's death scene was much sadder script-wise, because he gives a lengthy-dying speech at the end of his long, full life.
The sadness during Itachi's death was completely through imagery, no words were spoken, but you can clearly tell a part of sasuke had died there along with his brother, and its not until tobi begins explaining Itachi's true motives that words are connected with that imagery. and Tobi kind of evn ruins THAT by telling more half-truths.
