A section is a cut through the 3d-model. An elevation is different. It shows the face of something, or perhaps more correct, the projection of an object/s to a plane.
Project Definition: Establishing Scope, Vision and Work Effort. In order to have any realistic shot at a successful project, (delivered on time and on budget) the overall vision and work effort must first be fully defined --- i.e. broken down into small, manageable and actionable parts.
According to the PMBOK (Project Management Body of Knowledge) 3rd edition, A project is defined as a temporary endeavor with a beginning and an end and it must be used to create a unique product, service or result.