What is the difference between different GPON board?

Both the H901GPSF and H901GPHF boards are 16-port GPON interface board. Both of them can provide GPON access services together with optical network units (ONUs).

The main difference is capacity, GPFD is 16-GPON Port board, GPBD is 8-GPON Port board.

The main difference is capacity, GPFD is 16-GPON Port board, GPBD is 8-GPON Port board.
Huawei GPBD Board Thunder link com

B+ Module C+ Module Type One-fiber bi-directional optical module, class B+ One-fiber bi-directional optical module, class C+ Operating Wavelength Tx: 1490 nm
Rx: 1310 nm Tx: 1490 nm
Rx: 1310 nm Encapsulation Type SFP SFP Port Rate Tx: 2.49 Gbit/s
Rx: 1.24 Gbit/s Tx: 2.49 Gbit/s
Rx: 1.24 Gbit/s Minimum Output Optical Power 1.50 dBm 3.00 dBm Maximum Output Optical Power 5.00 dBm 7.00 dBm Maximum Receiver Sensitivity -28.00 dBm -32.00 dBm Optical Connector Type SC/PC SC/PC Optical Fiber Type Single-mode Single-mode Reach 20.00 km 20.00 km Overload Optical Power -8.0 dBm -12.0 dBm Extinction Ratio Huawei GPBD Board Thunder link com

Boards released later can replace boards released earlier and 8-port boards can replace 4-port boards. Specifically,
GPON: H805GPBD can replace H802GPBD and H801GPBC; H802GPBD can replace H801GPBC.
The above replacement is not limited by version and no additional data is required. Except for the above replacement, if a 4-port PON board needs to be replaced with an 8-port PON board, the slot data must be cleared first. Otherwise, the PON board cannot be registered.
Huawei GPBD Board Thunder link com

H802GPBD Board
The H802GPBD is an 8-port GPON OLT Interface Board. It works together with the optical network terminal (ONU) to provide GPON access services.
H805GPBD Board
The H805GPBD is an 8-port GPON OLT Interface Board. It works with the optical network terminal (ONU) to provide GPON access service.
Huawei GPBD Board Thunder link com

GPFD is a 8 port GPON interface card of Huawei OLT, provide GPON service access from ONT. GPBD can maximum access 8*128 GPON subscribers. GPBD has different part number like H80D00GPBD01, H80D00GPBD02 etc, but basically you only need to identity H802GPBD, H805GPBD, H806GPBD H807GPBD version, and with B+ or C+ SFP module. Huawei GPBD Board Thunder link com Huawei GPFD boards Thunder link com

Oh, I also have this kind of problems, and one of my friend introduce me to read this article: What's the Difference between GPON and EPON? http://www.huanetwork.com/blog/whats-the-difference-between-gpon-and-epon/

MA5603T is multi service based while MA5683T is just OLT, MA5603T can support service like ADSL, VDSL, GPON etc, while MA5683T only supports GPON, P2P etc, but their hardware and configuration command is the same.
Note: both can't support AC power, but you can purchase a telecom level AC to DC converter if you just have AC power source.
MA5683T Price and Specs Huawei SmartAx OLT MA5683T Huanetwork com