Simplify the following text for a Grade 9 native English-speaking person.
Original: The division between the Hutu and the Tutsi ( the larger of the other two groups ) is based more upon social class than ethnicity , as there are no significant linguistic , physical , or cultural differences between them .
Simplified: The division between the Hutu and the Tutsi ( the larger of the other two groups ) is mainly based on social class , not ethnicity .