What are the limitations of a contingent worker?

I'm using Oracle Fusion. In the few occasions when we've hired contingent workers, they've run into limitations not being able to access content that employees with the same roles have no problem accessing. One example is when one contingent worker was given expense delegation access for other employees but they received an error when accessing the Me→Expenses screen. Is there a list of screens/functionality that is not available to contingent workers?