Autotrophic refers to a kind of organism that can maintain life activities by using organic matter synthesized by itself. Photosynthetic autotrophy is an important autotrophic way, which refers to the process of transforming inorganic substances into organic substances by using light energy and carbon dioxide, and releasing oxygen at the same time. Another autotrophic way is chemical autotrophic. In this case, organisms make organic matter by using inorganic substances such as ammonia and sulfide. Heterotrophication means that organisms can't maintain their life activities by synthesizing organic matter by themselves, but need to ingest synthesized organic matter from the external environment to obtain nutrition.

The difference between autotrophic and heterotrophic is as follows:

1. Different nutrient sources: autotrophs mainly use inorganic synthetic organic matter as nutrient source, while heterotrophs needs to absorb synthetic organic matter from the external environment as nutrient source.

2. Different energy conversion methods: autotrophs can use energy, such as sunlight or chemical reaction, to convert inorganic substances into organic substances and store energy; On the other hand, heterotrophs can get energy directly from the food of other creatures.

3. Different biological forms: Autotrophic organisms are usually plants or unicellular organisms, and heterotrophs is dominated by animals, including humans, mammals and birds.