EPON, Ethernet Passive Optical Network, and GPON are very similar in the sense that they are both PON networks, both utilize fiber optic cables as well as the same optical frequencies. Both networks have a rate of roughly 1.25 Gbits/s in the upstream direction, however this is where the two differ from one another. One of the main reasons why GPON was created was to have a higher bit rate in the downstream direction. While an EPON downstream transmission rate has the same rate as its upstream, 1.25 Gbit/s, GPON has a downstream rate of 2.48 Gbit/s. 

BPON, Broadband Passive Optical Network, and GPON are similar as well in the same aspects above. They both utilize fiber optics and can serve 16 to 32 users. BPONs specifications follow ITU-T G983.1 while GPONs follows ITU-T G984.1. When PON applications started being introduced, BPON was the most popular.