XG-PON: 10-Gigabit-capable passive optical network, provides asymmetric 10G transmission (Maximum downstream line rate: 9.953 Gbit/s, Maximum upstream line rate: 2.488 Gbit/s ).

XGS-PON: 10-Gigabit-capable symmetric passive optical network, provides symmetric 10G transmission (Maximum downstream line rate: 9.953 Gbit/s, Maximum upstream line rate: 9.953 Gbit/s ).

The figure above shows XG-PON and XGS-PON service boards, the service boards that support XGS-PON also support XG-PON.