let assume you have two destinations and are reachable by 4 links. You have total 16 packets which will travel from localtion A to B.
A ----Link 1----B
----Link 2 ---
During case of load balancing all the 16 packets will equally distributed by 4 links and each link will be having 4 packets.
Definition: Load balancing is a mechanism that helps to make networks more efficient. It distributes the processing of traffic evenly across a network with multiple-paths, in order to get optimal resource utilization, maximize throughput, and minimize response time.
A ----Link 1-(4 packets)---B
----Link 2 -(4 packets)--
----Link 3--(4 packets)--
------Link 4-(4 packets)--
During the case of load sharing all packets could travel the on link. Sometimes this could create a congestion on link too.
Definition: It is inherent in the forwarding process of a router to share the forwarding of traffic, if the routing table has multiple paths to a destination. If equal paths, the forwarding process will decide the manner of forwarding, still with the possibility of unbalanced forwarding. If unequal paths, the traffic is distributed inversely proportionally to the cost of the routes. That is, paths with lower costs (metrics) are assigned more traffic, and paths with higher costs are assigned less traffic.