set_max_capacitance
set_load - Sets the capacitance to a specified value on specified ports and nets in the current
design.
set_max_capacitance - Sets the max_capacitance attribute to a specified value on the specified ports and designs.
set_load is usually used to set what capacitance there is on an output (i.e. the external capacitance that exists and can't be changed)
set_max_capacitance sets the maximum capacitance that will be allowed on the specified net. If the tool calculates there is more capacitance than this limit, it will try to change the circuit to reduce the capacitance below this limit. Obviously it can't change the capacitance set by the set_load command, but it can change internal circuitry - by buffering, resizing cells etc.