Complex sentence: The kyū ranking system varies from art to art and school to school: while in some arts, all the kyū-level practitioners wear white belts, other arts use different coloured belts, tags or stripes to mark kyū grades.
Split into simpler sentences: The kyū ranking system varies from art to art and school to school. In some arts, all the kyū-level practitioners wear white belts while in others different coloured belts, tags or stripes are used to mark kyū grades.