What is the difference between selfishness and self$-$interest, if any?

Self$-$interest concerns only the individual and places his or her needs and concerns above those of others, whereas selfishness concerns all matters that relate to the individual.

Selfishness concerns only the individual and places his or her needs and concerns above those of others, whereas self$-$interest concerns all matters that relate to the individual.

They are the same.

Self$-$interest concerns only the greatest net happiness for all of those concerned, whereas selfishness concerns the greatest happiness over the long run for all of those concerned.