Persons refers to a group of individuals, considered separately, e.g.: There are three persons who are suspects in that crime.
People refers to a group as an entity, or to individuals in the abstract, e.g.:
People respond to kindness better that to anger or
The people of New Jersey voted for a new governor. 'People' can generally be used in either case, but 'persons' is never used to refer to collective of abstract entities.
