Product Log Contains Story and Task. A story is typically functionality that will be visible to end users. Developing it will usually involve a programmer and tester, perhaps a user interface designer or analyst, perhaps a database designer, or others. It would be very rare for a story to be fully developed by a single person. (And when that did happen, the person would be filling multiple of those roles.)
A task, on the other hand, is typically something like code this, design that, create test data for such-and-such, automate that, and so on. These tend to be things done by one person.