Work packages are components of the WBS that are small enough to effectively estimate for budget and resources, and input into the project schedule process.
The tasks are on the schedule and represent the more detailed and sequenced steps with dependencies that will complete the work packages and contribute to the overall schedule. Completion of a work package may result in a deliverable -- something concrete showing progress on the project.
The deliverables are the intermediate and final concrete things that are to be delivered. The ultimate project deliverable is the new product or service the project set out to create. The deliverables may be components that go into assembling the final product, for example.