Source/Destination
tab helps find the traffic from an individual host passing through a
specific interface. The Source table will group all the source IP
address in the conversation and the total traffic contributed by that
host will be displayed. You can further drill down to an IP address/host
to view the destination host with the application used and the amount
of traffic transferred. This would be the same for Destination tab also.

Many
customers have doubts regarding the IP that is shown as the top
contributor under the conversations tab is not the top contributor in
the Source/Destination tab. This is because, the conversations tab
lists every conversation happened whereas the Source/Destination tab
will group those conversations based on Source/Destination IP address.
When grouping is done, the top IP in the conversation might have less
traffic compared with the other IP address. So, combining the
conversations results in traffic difference in this tab.

This
tab accounts for the IN and OUT traffic of an interface separately. For
example let