Difference between LIQUID_FLOW and RICHARDS_FLOW

Hello everybody,

does somebody know the difference between LIQUID_FLOW and RICHRADS_FLOW?
As I found out both processes can be used for unsaturated zones. The primary variable is in both cases pressure.

Thank you!

RichardsFlow uses the Richards equation whereas the LiquidFlow process does not have
saturation as secondary variable.
However, these are not the processes I use on a regular basis, so I might not be fully aware of their full feature list, but you’ll get more insight if you’ll take a look at the benchmark page as it contains the corresponding equations and input files.