What is the difference between a autotroph and a heterotroph?

An autotroph is a producer.  It makes its own food, and doesn't require outside sources to bring it food in order to stay alive.  An example of an autotroph is plants.  They make their own energy using photosynthesis.

On the other hand, a heterotroph is a consumer.  It cannot make its own food, and requires outside sources to bring it food in order to stay alive.  An example of a heterotroph is humans.  They receive their energy from food sources that they did not product themselves.