A motive or need "paves the way" for behavior. Life motivesrefer to the intention or meaning of the behavior and express values. For example, when a child plays a game for fun, the child's desire/need to "have fun" grounds his action: it is the child's intention in playing and the psychological meaning of his behavior -with the motive also showing that the child values having fun.
As Aristotle already found, motives can be distinguished into means and ends. Means thus serve only as "mediating" intermediate steps to get what we want -they motivate only insofar asthey create or enable something else.
In contrast, purposes are what people really or "ultimately" want: Food, for example - or status, power, and revenge. When a hungry person buys food, foodis the "ultimate motive" -when a swimmer enters a competition, winning is his goal.