What are the differences from FGSW-2402PVS, FGSW-2620PVS and FGSW-2612PVS?

For switch function, the three switches provide with 24 10/100Mbps TP ports. FGSW-2402PVS has 2 open slots for 10/100Base-TX, 1000Base-T and 100Base-FX, 1000Base-SX/LX fiber-optic interface. FGSW-2620PVS and FGSW-2612PVS have 2 fixed 10/100/1000Base-T RJ-45, SFP (mini GBIC), either TP or SFP.
For PoE function, FGSW-2620PVS and FGSW-2402PVS support 24 Power over Ethernet injector TP ports, that is, all the 24 10/100Mbps TP ports can supply 48VDC power to IEEE802.3af compliant Ethernet devices. The FGSW-2612PVS support only 12 Power over Ethernet TP ports. Only first 12 TP port support PoE function.