Think of a pool as a group of records. As you know, a single DNS record points to a single IP address. Whereas, a record pool cycles through multiple IP addresses in a round robin fashion. In this case, a group of DNS records.
Pools were created to make your job easier. Specifically, DNS load balancing which manages how traffic flows to multiple endpoints. And best of all, pools can be combined with a bunch of our other services like Failover, GTD, and our new performance load balancing service to make some cool load balancing configurations.