Both the TPS25820 and TPS25821 are source (i.e. DFP) Type-C port controllers with integrated power switches for VBUS. The TPS25820 also has integrated power switches for VCONN. Refer to the functional block diagrams (Figure 10 and Figure 11). The TPS25820/21 devices do not support BC1.2 charging modes, because it does not interact with USB D+ and D– data lines. However supporting DCP mode of BC1.2 can be easily accomplished in data-less ports like wall chargers and CLAs by simply tying a 100-Ω resistor between the D+ and D- pins of the Type-C connector.
The TPS25820 has a built-in VCONN current limiting switch and can be used to implement USB 3.1 DFP, whereas the TPS25821 does not implement a VCONN current limiting switch hence is used in the implementation in USB 2.0 DFP ports or as a USB source only port. Other than the VCONN current limiting switch there are no other functional differences between the TPS25820 and TPS25821.