The BL36 is a Brush LESS motor system (the motor has no brushes inside it), This is "top of the line"  & (our best seller ) You can buy either at the same price. This (BL-36) is the only one we recommend (see reasons below).

The BR-36 is a Brushed motor system (has brushes on the inside) AND WE DON'T RECOMMEND YOU BUY THIS ONE 

• You will get 20 - 25 % more range out of your battery pack with a BL36 system(compared to the brushed BD36).
• You will never have to change the brushes inside the motor of the BL-36.
• You get a 50 amp controller with the BL-36 rather than the 20 amp you would get with the brushed