What is the difference between a autotroph and a heterotroph

Autotroph: an organism that is able to form nutritional organic substances from simple inorganic substances, such as carbon dioxide

Heterotroph: an organism deriving its nutritional requirements from complex organic substances

An autotroph is an organism that prepares its own food using simple organic materials whist a heterotroph is an organism that cannot prepare its own food but depends on other organisms for survival.