So basically, Anime Lucy and Manga Lucy are different characters personality-wise. I wanna list some of their key differences with some examples because I have time to kill heh
Also spoiler alert
Manga Lucy:
•is generally more sadistic (laughs at Mariko after cutting off her legs in Chapter 70, laughs at Bando during their first encounter in chapter 6, laughs at Nana while tearing her arms off in chapter 15, laughed at Kouta when she murdered his family)
•has commited far more atrocities than her anime equivalent (has a confirmed body count in the thousands, attempts to destroy a city by the end)
•tends to actively seek out to harm others when given the chance (a trait that's also in her anime equivalent, but is bumped up to 11, like when she attempts to murder Mayu in chapter 77)
•is way more cocky and overall less strategic in her battles: gets angry far more often when fights go south (which you could argue is more realistic, since Lucy has rarely had any battles with Diclonii/trained individuals until this point: she charges after Mariko in chapter 69 after Mariko punches her for example)
•is far more destructive than her anime equivalent, starting out with 14 vectors (later gaining 14 more vectors during the finale, giving her a grand total of 28 near the end)
•has 3 personalities total: Lucy, Nyu, and the DNA Voice
•Nyu allegedly tried to convince Lucy that she could coexist with humans in chapter 99, idk how that works
•generally only cares about the Maple Inn due to Kouta residing there: heals him in chapter 103 before melting
•is revealed to have been named Kaede by the second to last chapter
•has a half-brother that she kills and apologizes to in chapter 91 because she believes their species shouldn't continue
•learns about her mother's fate
•is horrified to learn that the DNA Voice can control her body
Anime Lucy:
•is generally more apathetic, committing the same crimes as her manga equivalent but doesn't show nearly as much expression or amusement (at least until the manga and anime branch out halfway through: doesn't laugh at Bando during their encounter in episode 2, doesn't laugh at Nana while tearing her arms off in episode 4)
•is weaker than her Manga equivalent, only has 5 vectors
•develops some restraint by the end of the series (doesn't kill Bando during their final encounter, doesn't kill Mayu in episode 10 when she interferes twice during the fight between Lucy and Nana)
•saves Nana from Isobe in episode 13 and tells her to live at the Maple Inn: in the manga, Lucy only saves Nana by coincidence when she fights Mariko's clones in Chapter 84
•gets to kiss Kouta goodbye in the final episode
•only has 2 personalities: Lucy and Nyu
Personal Opinion Corner~
If I'm being honest I had a hard time liking Lucy from the manga.
She was way too sadistic for my taste, and the main reason why she got herself into trouble all the time is because she tends to either direct her attention elsewhere (tries to kill Mayu instead of turning her attention to Bando or Nana in chapter 77) or tortures her opponents instead of just finishing them off (the Mariko clones knock one of her horns off in chapter 84 because she spent a lot of time chucking objects into them, she only kills one outright)
She never learns that this way of combat screws her over, even in situations where it blatantly fails her (Bando was able to outsmart Lucy during their rematch because he could dodge and predict her vectors in chapters 76/77)
Though she still has this flaw in the anime, it's way less frequent due to its length, and I liked her character way more because she wasn't reveling in the pain she caused to her opponents