Simulation models are abstractions of reality. Each possible aspect may be represented at a given level of detail. The level of detail is sometimes constrained by simulation tools. Still, choosing the right level of detail for a simulation exercise is a fundamental part of the art and science of simulation.
Equation-based modeling allows the individual equations describing component behavior to be combined and modified. With component behavior being described by equations, variables do not need to be inputs or outputs anymore, which makes it possible to model situations of flow reversal in an easier way than with typical component-based models. The flexibility of equation-based modeling has been praised for particular applications such as the modeling of controls in HVAC simulation.