Carlotta
>uses gem magic to shoot bullets
>born from a noble house, red theme, and same JP voice
>She even left you a red gem as a memento in your special inventory

Phrolova
>fully awakened her powers after death
>killed a lot of people
>forgiven because she's dindu

The difference
>It was Carlotta who was adopted by the Montelli instead of the other way around

Bros, Wuwa ver.2 upwards really is the secret Fate/Stay Night collab we've been waiting for.