Single Path protocols learn routes and select a single best route to each destination. These protocols are incapable of load balancing traffic. An example of a single-path protocol is standard Border Gateway Protocol (BGP). BGP will advertise only the single best path it knows to a destination. It will only insert a single path to a destination in the IP routing table. However, today there is eBGP Multipath, which allows BGP to perform load balancing by creating equal cost paths.
Multi-path protocols learn routes and can select more than one path to a destination. These protocols are better for performing load balancing. OSPF, RIP and several other protocols will learn several best paths and will route traffic accordingly, dividing up the bandwidth based on the protocol's metrics, or on the administrator's configuration.