M.D. is the abbreviation for mano destra, or the right hand; M.S. is the abbreviation for mano sinistra, the left hand. It indicates that the notes can or should be played with either the left or right hand. These indications are usually suggestions from the composer or editor and does not necessarily need to be followed.
As for the "stars", it may very well be pedal markings, which usually means to lift the damper pedal. It will most often be preceded by a "Ped" indication, to depress the damper pedal.Just like the hands distribution indications, pedaling indications in the score are also just suggestions.
Out of curiosity, what kind of device allows you to type and read this forum?
Which piece of music are you referring to? There is no standard notation regarding this so there is no difference.