Conceptually, autotrophs refer to organisms that can synthesize organic matter from external inorganic substances, such as green plants and nitrifying bacteria.

Heterotrophs is an organism, such as human, which can't synthesize organic matter from external inorganic substances by itself, but can only get energy by eating.

Therefore, the fundamental difference between autotrophs and heterotrophs is that.

Whether you can synthesize organic matter from external inorganic matter by yourself.