1 word experience
Itachi has had MS Sharingan for like since he was 13 and he died when he was like 21 or so. Like he had MS for 7 years whereas Sasuke hasn't even mastered the full power of the Sharingan. Sasuke had MS Sharingan for a week then he got EMS Sharingan whereas he hasn't event had time to unlock PS Susanoo maybe if you gave Sasuke 1 year he would have mastered his EMS and unlock PS Susanoo.
Itachi has a fully matured MS Sharingan while Sasuke is new to the system cause he got EMS in a week
This why mostly Itachi>Sasuke
But we all know Rinnegan Sasuke>Itachi
Itachi has had MS Sharingan for like since he was 13 and he died when he was like 21 or so. Like he had MS for 7 years whereas Sasuke hasn't even mastered the full power of the Sharingan. Sasuke had MS Sharingan for a week then he got EMS Sharingan whereas he hasn't event had time to unlock PS Susanoo maybe if you gave Sasuke 1 year he would have mastered his EMS and unlock PS Susanoo.
Itachi has a fully matured MS Sharingan while Sasuke is new to the system cause he got EMS in a week
This why mostly Itachi>Sasuke
But we all know Rinnegan Sasuke>Itachi