Here we compare the optical properties of porous particles of two kinds: . ... Below we show the behaviour of the efficiency factors Q ext (x), Q sca (x), Q abs (x), the asymmetry parameter g (x) and albedo (x) as well as for x = 3 and 100 the phase function i (theta) and polarization of scattered radiation p (theta) for different values of the parameters m and P . ... factors . ... Qext(x) . Qsca(x) . ... i (theta) . ... albedo (x) . ...