A food chain and a food web both describe the flow of energy and nutrients through an ecosystem, but they differ in their complexity and scope. Here's a brief explanation of each:

Food chain: A food chain is a linear sequence of organisms that shows how energy and nutrients are transferred from one organism to another. It usually starts with a primary producer, such as a plant, and ends with a top predator, such as a carnivore. Each organism in the chain is dependent on the organism before it for food and energy. For example, a simple food chain in a grassland ecosystem might be: grass → grasshopper → mouse → snake → hawk.

Food web: A food web is a more complex and interconnected network of food chains that shows the relationships between multiple species in an ecosystem. It consists of many food chains that are interconnected and overlapping, with each organism occupying multiple positions in the web. A food web takes into account the fact that many organisms in an ecosystem feed on multiple species and are themselves eaten by multiple species. For example, a food web in a forest ecosystem might show how a single species of bird might eat insects, fruit, and seeds, while being preyed upon by multiple species of predators.

In summary, a food chain is a linear sequence of organisms that shows how energy and nutrients are transferred from one organism to another, while a food web is a more complex and interconnected network of food chains that shows the relationships between multiple species in an ecosystem. While a food chain follows a single path of energy flow, a food web takes into account the many different interactions that occur in an ecosystem.