Just wanted to start a discussion on small differences (and large) between popular manga and their anime adaptations (not filler, differences in main story)

I have recently started reading the One Piece manga, after getting impatient with recent episodes.

For example, when Luffy meets Blackbeard in Jaya, Marco (1st commander for White Beard pirates) is not introduced in the anime, instead there is a generic black haired member of White Beard's crew (Marco is blond). Not really spoiler so I'll leave as is

Another example in One Piece is how Honor Zef lost his leg:
Spoiler:

In the anime I'm pretty sure his leg was caught in the anchor's chain when he dived into the ocean to rescue Sanji (correct me if wrong), whereas in the manga he eats his own leg so he does not starve


I am fairly up to date in the anime for most of the longer shonen series, but have not read their respective manga (eg Naruto/Bleach) and was just wondering if any major (or minor) changes happened as they were animated. Small OCD where I wanna know it all, but am too lazy to start from scratch again with longer series

Two series with some big deviations that come to mind are Berserk (no puck, no zombies in the forest, etc) and Gantz (though the changes were mostly to compensate for the end becoming fillers)