Definition: Simulation
Computer simulations use computer models to also predict how a system will behave given a set of conditions. Again, they are created through mathematical formulas.
The difference between a model and a simulation is that a simulation often uses something physical to mimic the system.
A very good example of a simulation is a flight simulator.
Another example of a simulation is a thrill ride simulator somewhere like Disneyland.
Another form of simulation is Virtual Reality.