No I don’t mean they’re copies of each other. Instead, they’re the two sides of the SAME coin.
Both stories portray the theme of what power does to someone and how they let the power affect their primary goal.

WHAT POWER DID TO LIGHT : It corrupted him and his goal, stripped him of his humanity then got him betrayed by his own ideals in the end.
WHAT POWER DID TO LELOUCH : It destroyed his mental, challenged his goals and ideology. But he NEVER lost the sight of his goals and humanity.

LIGHT’S GOALS AND HOW IT GOT CHANGED IN THE END
Light never truly stopped what he set out to do. It was his ideology and intent that is, crushing who tries to get in his way, going against his own goals by being a complete hypocrite in the way he kills. This brought him to his end.
LELOUCH’S GOALS AND HOW IT GOT CHANGED IN THE END
He never truly wanted to save the world. He just wanted to crush the world his father made as a revenge for the life he and his sister lived. He grew past this dream in the end and set out to be a martyr. A true selfish yet selfless sacrifice.

Lelouch’s final goal coincides with Light’s original ideology, and in a way, Light’s selfishness in the end also coincides with Lelouch’s mindset at the start.
It was the execution which made Lelouch a much better character than Light. In the end, it all comes down to who was written better and it’s clearly Lelouch vi Britannia.

Both of them are amongst my favorite characters of all time. They’re also the two protagonists who I believe could be considered the most intriguing MCs in anime.
I’d give Lelouch a 9 and Light a 8.5 out of 10. Both are really amazing though imo.