Various frameworks are available for modeling an organizational setting. Their constituting models nevertheless mostly choose a particular decision level to represent perceived reality meaning that some introduce coarse-grained (i.e. abstract) elements and some others fine-grained (i.e. detailed) ones. Sometimes, in a same model, elements of various levels of granularity can be mixed like for example in the i* strategic rationale model. The main drawback is that this leads to hard to read and complex models, not ideal for easy and quick understanding of the software problem. Also, within the industry, poor unification in the use of models does exist. The various Unified Modeling Language (UML) models and the Business Process Model and Notation (BPMN) are nevertheless rather popular. In this paper, we study the use of the Business Use Case Model – an extension of the classical UML use-case model defined in the Rational Unified Process (RUP) – and the BPMN Business Process Model (BPM) as a unified framework for knowledge representation at strategic, tactical and operational levels. By default, the RUP advises to use UML activity diagrams for operational-level knowledge representation. Their main drawback is that they have been engineered to model software behavior with respect to the user and not business process modeling at large. The BPMN BPM thus offers more perspectives for pure business process modeling; that is why it mostly used in the industry for this purpose. The use of these models in a unified way is ensured by traceability at the various levels of modeling.