XG-PON (10G down / 2.5G up) – ITU G.987, 2009. XG-PON is essentially a higher bandwidth version of GPON. It has the same capabilities as GPON and can co-exist on the same fiber with GPON.
XGS-PON (10G down / 10G up) – ITU G.9807.1, 2016. XGS-PON is a higher bandwidth, symmetric version of GPON. Again, the same capabilities of GPON and can co-exist on the same fiber with GPON.
NG-PON2 (10G down / 10G up, 10G down / 2.5G up) – ITU G.989, 2015. Not only is NG-PON2 a higher bandwidth version of GPON, it also enables new capabilities like wavelength mobility and channel bonding. NG-PON2 co-exists well with GPON, XG-PON, and XGS-PON.