This paper proposes a model to identify education and/or training emphasis for 3D Virtual Environments. Through a survey of such applications specific characteristics of each emphasis were identified. Although few authors highlight the distinction between Virtual Environments for Education and Training, the correct definition of each of these types can facilitate the attainment of educational goals for the niche one wants to accomplish. In this study a special focus is given to the training applications, with the proposal of a standardization of the "training modes" based on a functional conceptual framework. At the end of the article a case study of a desktop Virtual Reality (VR) system for training will be presented. This system includes a maintenance sub-system in a Hydroelectric Energy Unit, using a "learn by doing" approach