Process simulation and modelling:

What is the difference between Process Simulation and Modelling?

"Process simulation is a subset of process modelling"

The 'process lifecycle'

A process can be considered to have a lifecycle, from the time it is conceived (conceptual design), through the various R&D and engineering phases to commissioning and operation and finally decommissioning

Process simulation and process modelling refer to different things.

Process modelling is the art or activity of building a mathematical model of the process (or of a product, for that matter) by describing its fundamental physical and chemical relationships – without specifying how they are to be solved.

Process simulation is merely one of the activities that you can perform with that process model.
Process simulation is often an exercise in 'molecule accounting', and as such is often performed by relatively junior engineers.

Construction of a high-accuracy process model, on the other hand, requires deep modelling and process expertise, and is usually performed by an experienced specialist – sometimes working in conjunction with R&D personnel.

A powerful general-purpose process modelling tool has a role to play in every one of the stages, not just simulation of the process end engineering designs.