Discrete-Event Simulation (DES) has become a commonly used tool for the modelling and analysis of logistics. A more novel approach to manufacturing problems is Advanced Planning Systems (APS). These are used in an optimization process for the planning of production, inventory, and transportations often integrated with ERP-systems. Supply/Demand Chains can be approached from a strategic, tactical, or operational level. Simulation tools and APS-systems are different approaches to a similar problem. The simulation approach involves connecting an Enterprise Resource Planning (ERP) system with a simulation system. The simulation system contains a model of the production, and 'real-time'-data is used to produce a realistic production plan, e. g. to minimize waste of resources, or setting more accurate delivery dates. APS-systems are using simultaneous data when considering resource allocation. APS-systems normally use a separate module for calculation and optimization. The optimization activity produces an improved plan where trade-offs are examined. In this paper a conceptual model is proposed and an overview is given on the two software tools, and their advantages and disadvantages. Their usefulness is discussed in the context of physical material flow in Supply Chain (SC). Finally some results and experiences from industrial simulation studies are presented.