these are different things: ibis defines C_Comp and C_Pk.
C_Comp : "This is the silicon die capacitance and does not account for package capacitance. It is the capacitance seen when looking from the pad back into the buffer". C_Pk represents the package capacitance.
Check this out: http://www.analog.com/media/en/technical-documentation/application-notes/59359416714120559501529785432450718322963858076…
Cin and Cout from the datasheet represent the internal capacitance of an input/output. hope this helps. ibis doesn't define Cin Cout