An agent is capable of interaction with its environment, of perceiving changes in it, and of effecting changes by acting on it. A key characteristic of intelligent agents in autonomoy. Agents have architectures. An architecture of an agent consists of a set of components and a set of connections among the components. Agents may or may not be physically embodied.
Robots too are examples of the same.
These agents are also called situated action agents or reactive control agents. The world is perceptually accessible. The question is not which is the correct design for intelligent agents. For example, an artificial frog that catches artificial flies may well be based on the first design above because the world is perceptually accessible, but there is great need for rapid processing.