Simulation is the prediction of some variables in a system, given some boundary constraints or conditions.

A simulation is an imitation of the dynamics of a real world process or system over time.

A model is a translation of a real world system/problem into another language, like mathematics or programming.

A model is a formal translation of a system.

Traffic simulation is the mathematical modeling of transportation systems through the application of computer software to better help plan, design and operate transportation systems

Traffic simulation models are a formal representation of transportation systems that allow to represent the operation of the system by simulation.