A project schedule is a timetable that shows the start and end date of all project tasks, how the tasks relate to each other and usually which team members or other resources are responsible for delivery.
It is a dynamic document that is created during initial the planning stage. The approved project schedule acts as a baseline to work to, but it is maintained and updated throughout the project as things change.
A project plan is a series of formal documents that define the execution and control stages of a project. The plan includes considerations for risk management, resource management and communications, while also addressing scope, cost and schedule baselines.