Let me first explain to you about the agent because all the terms that you are asking are related to it.
An agent is a thing that can be viewed as:
– perceiving its environment through sensors and
– acting upon that environment through actuators.
a) Atomic Representation: In this representation, each state of the world is a black box that has no internal structure. E.g., finding each state is a city. AI algorithms: search, games, Markov decision processes, hidden Markov models, etc.
b) Factored Representation: In this representation, each state has some attribute value properties. E.g., GPS location, amount of gas in the tank. AI algorithms: constraint satisfaction, and Bayesian networks.
c) Structured Representation: Relationships between the objects of a state can be explicitly expressed. AI algorithms: first-order logic, knowledge-based learning, natural language understanding.