Model and a simulation
I'm grateful to proto-knowledge for this 
A model is a product (physical or digital) that represents a system of interest. A model is similar to but simpler than the system it represents, while approximating most of the same salient features of the real system as close as possible. A good model is a judicious tradeoff between realism and simplicity. A key feature of a model is manipulability. A model can be a physical model (for example a physical architectural house scale model, a model aircraft, a fashion mannequin, or a model organism in biology research); or a conceptual model (for example a computer model, a statistical or mathematical model, a business model.
Modeling is the act of building a model.
A simulation is the process of using a model to study the behavior and performance of an actual or theoretical system. In a simulation, models can be used to study existing or proposed characteristics of a system. The purpose of a simulation is to study the characteristics of a real-life or fictional system by manipulating variables that cannot be controlled in a real system. Simulations allow evaluating a model to optimize system performance or to make predictions about a real system. Simulations are useful to study properties of a model of a real-life system that would otherwise be too complex, too large/small, too fast/slow, not accessible, too dangerous or unacceptable to engage. While a model aims to be true to the system it represents, a simulation can use a model to explore states that would not be possible in the original system.
Simulating is the act of using a model for a simulation
- Explain the difference between a model and a simulation.
Devote time and attention to gaining knowledge of (an academic subject), especially by means of books
Undertake a systematic process of discovery
Give a detailed account including reasons or causes.