HI Parvinder,
Yes there is a difference between the two.
Per packet load balancing disables the forwarding acceleration by a route cache, as the route cache information includes the outgoing interface. For per-packet load balancing the forwarding process determines the outgoing interface for each packet by looking up the route table and picking the least used interface. This ensures equal utilization of the links, but is a processor intensive task and impacts the overall forwarding performance.
The design of Cisco Express Forwarding includes enhancements that allow to use load balancing without sacrificing forwarding performance even when using per packet load balancing. Previously per packet load balancing required disabling of route-caching mechanisms like fast switching or optimum switching.
So CEF switching does not compromise on performance.
HTH
Ankur
