Today I would like to explain the difference between character development and character progression in One PEacce. So Nami accepting Luffy's help, is a character progression, because she is accepting the aid of pirates, whom she previously scorned due to her trauma with the Arlong Pirates. Progression marks a change in character. Development is where we learn about a character. So, for example when Luffy slams his foot on the bar to prevent Usopp from inquiring about the One Piece, this is character development. We now know to what extent Luffy desires this to be an adventure; and that also feeds into the central themes of what One Piece is, which is that it's about the adventure more than the destination. Another example is Luffy breaking out of the barrel at the beginning and telling Coby, that if he dies, then he dies. Nothing he can do about that. This is development. Luffy punching Vivi to explain to her that people will inevitably die in a civil war and the best course of action; and only thing they can really do to put an end to it is by kicking Crocodile's ass. This is all development. So Luffy was marked with progression after the events of Sabaody Archipilago, and then we saw that development in the early stages of Dressrosa