Difference between original broadcast and Special Edition (OVA)


There seems to be a difference in narrator for different versions of Code
Geass' ending. One is narrated by Kallen, another narrated by C.C.

Which version is narrated by which person, and does it bring a tonal
difference to the ending? Also, are there other significant changes between
the original broadcast and the Special Edition (OVA) of Code Geass?

