Regarding the differences in the source code: Gavin Andressen completely rewrote it in 2010, so that less than 1/3 of Satoshi's original code was left, and subsequent rewrites over the years to move to C++11 and later to C++17 have left almost no fragments of Satoshi code left intact.
Thanks for the detail! I should have mentioned that I compared the next versions of early Bitcoin source code (0.1.0 and sourceforge commits) to focus better on the writing style of Satoshi. I imagined that people worked so much on Bitcoin that almost no fragments of Satoshi code left intact. By the way, thanks again for the merit.