**Autotrophic Nutrition:**

Autotrophic nutrition is the mode of nutrition in which organisms produce their own food using simple inorganic substances such as carbon dioxide and water. Autotrophs are self-sufficient and do not rely on other organisms for their food.

**Heterotrophic Nutrition:**

Heterotrophic nutrition is the mode of nutrition in which organisms cannot produce their own food and depend on other organisms for their nutrition. They obtain complex organic substances as their food by either consuming other organisms or their products.

Now let's discuss the differences between autotrophic and heterotrophic modes of nutrition:

1. **Source of Food:**
- Autotrophs produce their own food through photosynthesis or chemosynthesis, using sunlight, carbon dioxide, and water. They convert these raw materials into glucose, which serves as their energy source.
- Heterotrophs, on the other hand, obtain their food by consuming other organisms or their products. They rely on the preformed organic compounds present in the environment.

2. **Energy Conversion:**
- Autotrophs convert solar or chemical energy into organic compounds during photosynthesis or chemosynthesis. They store this energy in the form of glucose or other carbohydrates.
- Heterotrophs obtain energy by breaking down the complex organic molecules present in their food. They extract the energy by the process of cellular respiration.

3. **Dependence on External Sources:**
- Autotrophs are not dependent on other organisms for their nutrition. They can synthesize their own food using simple inorganic substances.
- Heterotrophs are entirely dependent on other organisms for their nutrition. They need to consume other organisms or their products to obtain the necessary nutrients and energy.

4. **Role in the Ecosystem:**
- Autotrophs play a crucial role in the ecosystem as they are the primary producers. They convert sunlight or chemical energy into organic compounds, which are then consumed by heterotrophs.
- Heterotrophs occupy various trophic levels in the food chain and participate in the transfer of energy and nutrients within the ecosystem. They are consumers and decomposers, playing important roles in nutrient cycling.

In conclusion, autotrophic nutrition involves the ability of organisms to produce their own food through photosynthesis or chemosynthesis, while heterotrophic nutrition relies on the consumption of other organisms or their products for obtaining nutrients and energy. Autotrophs are self-sufficient, while heterotrophs are dependent on external sources for their nutrition.

2 differences that I know are