A Project is a temporary endeavour undertaken to create a unique product, service or result. This is the definition from the PMBoK guide from the PMI. A project is not a permanent fixture, including resources, budgets and teams, it is only in place to produce the final product. A project has a defined end and can be stopped, if the end is not going to be achieved or is no longer a business requirement.
A program is a set of related projects which are managed in a coordinated way to obtain benefits not available from managing the Projects individually. Programs will contain projects, but Projects may not necessarily be contained within a Program.