Producers are organisms that don't have to feed off of other living organisms to survive. They are self-sufficient. All plants are producers. They produce their own nutrients through photosynthesis.
Consumers are organisms that must feed off of other living organisms to survive. They can consume just producers (herbavoire), just consumers (carnivore), or both, like humans do (omnivore). They get their energy to function from other sources.
Basically, consumers eat producers.