Load balancing is a function used to divide the amount of work that a computer or a network has to do to accomplish a given task. In the case of pfSense, you can implement multiple ISP WAN connections and you can load balance your traffic between these connections. This means that when a device on the internal network makes a request to an external resource on a per-connection basis, pfSense can route the request over each WAN in a round-robin manner. If any gateway on the same tier goes down, it is removed from use and the other gateways on the tier continue to operate normally. Within the context of pfSense, a gateway is a system through which pfSense can reach the internet or another network.
Failover is basically the ability of a machine or a computer system to transfer an operation from a failed component to an alternative backup component without...