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.
While a program is defined as a predetermined group of projects that are related and are managed as one big task (in order to earn profits for the organization), a project is more or less temporary in nature that is undertaken to get specified results in given time along with constraints of cost and quality.