The difference between a bounce entry and a remote endpoint is in whether or not the leaf rewrites the outer source IP address of the packet. When a packet uses a normal remote endpoint, the Cisco ACI leaf uses its own TEP address as the outer source IP address, so the remote leaf learns this packet with its own TEP. When a packet uses a bounce entry, the Cisco ACI leaf doesn't rewrite the outer source IP address, so the remote data-plane learning will behave as if the packet came from the originating leaf rather than the intermediate "bounce" leaf.
https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric- infrastructure/white-paper-c11-739989.html