Simplify the following text for a Grade 13 native English-speaking person.
Original: Spirochaetes are distinguished from other bacterial phyla by the location of their flagella , sometimes called axial filaments , which run lengthwise between the bacterial inner membrane and outer membrane in periplasmic space .
Simplified: Spirochaetes are distinguished from other bacterial phyla by the location of their flagella , sometimes called axial filaments , which run lengthwise between the cell wall and outer membrane .