Difference between m-derived filters and constant k-filters?

in m derived impedance matching is possible but not in case of constant k filters. compared to constant k filter m derived filter has a sharp cutoff frequency.

in k type the attenuation is not complete in the stop band.where as in the m derived just beyond the attenuation rises to max just after the cut off frequency.

in m derived a capacitor and a inductor are taken in series at the output.