What is the difference between the fair and capacity schedulers?

Question

I am new to the world of Hadoop and want to know the difference between fair and capacity schedulers. Also when are we supposed to use each one? Please answer in a simple way be

Answer 1

Fair Scheduler, Allocates resources pools ( by weights), with fair sharing within each pool

Capacity Scheduler, Allocates resources to pools, with FIFO scheduling within each pool

The Capacity Scheduler is designed to allow sharing a large cluster while giving each organization capacity guarantees. with the possibility to excess capacity not being used by others.