Why are Beibei's clothes different from Yaya's?

Beibei is a sister, her hair and clothes are green, Yaya is her sister, and her hair and clothes are blue.

Beibei, the role in the animation "The Miracle Dance of the Little Devil Fairy" and its derivative works, is set as a lively, kind and positive character who can sing and dance well. She is the second princess of Gemini. Because Gemini was destroyed by Queen Haley, she fled to the human world with the night star box in a flying machine, which has the ability to gather stars and diamonds.

The role Ya Ya in "Miracle Dance of the Little Devil in Balala" and "Dream Melody of the Little Devil in Balala" is set as a brave, kind and positive character who can sing and dance well. Big princess, a Gemini, is also Beibei's twin sister. In order to protect her sister Beibei, she sacrificed herself and was imprisoned by Queen Haley. Whenever my sister encounters difficulties or dangers, she will communicate with Beibei through telepathy or the connecting stone given by the magic fairy king to help, guide and remind her sister.