Difference between primary and secondary groups are:

1. A primary group is relatively small whereas secondary groups are generally large size.
2. Members of primary group generally have face-to-face contact, and thus, have intimate and co-operative relationships, as well as strong loyalty. On the other hand members of the secondary group maintain relatively limited, formal and impersonal relationship with one another.
3. Unlike primary groups, secondary groups are specific or specialized interest groups. Generally, a well defined, division of labor characterizes these groups.
4. The primary group comes to an end, when one or more members leave it; they cannot be substituted by others. Member can be substituted and replaced, hence, a secondary group may continue irrespective of whether its original members continue to be its members or not.
5. In primary groups there are no end goals whereas in secondary groups there are long term goals.
6. In primary groups the behavior of the members are influenced by inner powers whereas in secondary groups the behavior is influenced by external factors.