"Violetchi", "Furawatchi" and "Leaftchi" are all names for the same character. You wouldn't pit them against themselves, would you?
Their different colors.
Violetchi is violet.
Furawatchi is pink
Leaftchi is green.
Furawatchi/Flowertchi is the japanese name.
Furawatchi is Leaftchi in USA Tamagotchis.
Violetchi is Furawatchi's name in European Tamagotchis.
They all are violet/light purple with yellow and dark blue flowers.
Some early full color arts of new Tamagotchi characters (back in 2004) showed Furawatchi as light green with red and blue flowers, but that was just early concept and they changed the colors later.