The key difference between autotrophic and heterotrophic is whether organisms can directly convert carbon dioxide into organic matter, if so, it is autotrophic, otherwise it is heterotrophic; Anaerobic or aerobic depends on whether oxygen is needed in the process of oxidizing and decomposing substances. Normal operation requires aerobic, anaerobic normal operation requires anaerobic (anaerobic breathing).

Photosynthetic autotrophy is a common green plant. Its assimilative energy comes from light, which can convert carbon dioxide into organic matter.

Chemotactic autotrophic bacteria are common, such as nitrifying bacteria, whose assimilation process energy comes from the energy released by the redox process of chemical substances, which can convert carbon dioxide into organic matter. This can be divided into four life types according to C and energy sources.

Photoautotrophic: this is the type of plants and some autotrophic bacteria with pigments, such as green S bacteria. They use inorganic CO2 as C source and light energy as energy, thus synthesizing their own organic matter.

Chemotactic autotrophy: Organisms, such as nitrifying bacteria, that use inorganic CO2 as carbon source and oxidize inorganic substances to generate energy.

Photoenergy heterotrophy: this kind is rare, which refers to organisms that use organic matter as C source and light energy as energy to synthesize organic matter.

Chemotaxis-heterotrophy: This is the nutritional mode of most animals and bacteria, which uses organic matter as C source and energy to synthesize its own organic matter.