Food Web:
A food web is a complex network of interconnected food chains that shows the flow of energy and the transfer of nutrients through different organisms in an ecosystem. It represents the feeding relationships among various organisms and how energy is passed from one organism to another.

Food Chain:
A food chain, on the other hand, is a linear sequence of organisms, where each organism is dependent on the one before it for food. It represents a single pathway of energy transfer in an ecosystem.

Differences:
1. Structure: A food web is a more complex and interconnected representation of feeding relationships, while a food chain is a simple linear sequence.

2. Number of Organisms: A food web involves a larger number of organisms compared to a food chain, as it includes multiple feeding relationships. A food chain, on the other hand, consists of a limited number of organisms.

3. Energy Flow: In a food web, energy flows through multiple interconnected pathways, allowing for more energy transfer and stability in the ecosystem. In a food chain, energy flows in a single linear path from one organism to another.

4. Realistic Representation: A food web provides a more realistic representation of the feeding relationships in an ecosystem, as it considers the multiple interactions between different organisms. A food chain, on the other hand, simplifies the interactions by focusing on a single pathway.

5. Impact of Species: In a food web, the removal or decline of one species can have a cascading effect on other organisms, as they are interconnected. In a food chain, the impact is relatively limited as it is a linear sequence.

6. Stability: A food web tends to be more stable and resilient to disturbances, as it allows for alternative food sources and multiple energy pathways. A food chain is more susceptible to disruptions, as any change in one organism can directly impact the entire chain.

Conclusion:
In summary, a food web is a complex network of interconnected food chains that represents the feeding relationships and energy flow in an ecosystem. It involves multiple organisms and provides a more realistic and stable representation of the ecosystem. On the other hand, a food chain is a simplified linear sequence of organisms, representing a single pathway of energy transfer. While a food chain is useful for understanding basic energy flow, a food web provides a more comprehensive understanding of the intricate relationships between organisms in an ecosystem.