Food portions are generally exchanged between persons who know each other. Gifts are usually given to poor persons with whom the giver is not acquainted.
Gifts are usually money.
Food portions are generally sent from home to home. The mitzvah of mishlo'ah manot provides an opportunity to repair the institution of friendship. Of course, this social improvement is not meant to occur only once a year. For there is no greater and nobler joy than bringing happiness to poor people, orphans, widows, and strangers. All I ask of you is that you love and honor each other.