What are some similarities and differences between Duncan and Malcolm in Macbeth?

In Macbeth, Malcolm feels very
dissimilar to his father Duncan.  Having fled Scotland for his own protection, Malcolm
at first refuses to return to Scotland when Macduff calls on him and tells him of all
the ills the people have suffered under Macbeth's rule.  Malcolm does not believe that
he has any of the "king-becoming graces" that his father possessed while he ruled. 
Instead, he feels that he is selfish, immature, and devious.  Macduff assures Malcolm
that Duncan would be very disappointed to know that Malcolm does not see rule as his
honorable duty.  Duncan was loved by all, and he was known as a fair and just king. 
Malcolm is eventually persuaded to return, but it is Macduff who takes down the tyrant
Macbeth.  Malcolm appears to have a softer hand than did his father, but both are loyal
to Scotland.