In what ways might the psychological contract between a company and its employees differ between these two workforces?

Provide three examples of how specific human resource management (HRM) practices would differ between an organization that employs highly-educated, well-paid, professional people on contract, to one that employs people with minimal formal qualifications on average wages via a union-negotiated collective agreement. In what ways might the psychological contract between a company and its employees differ between these two workforces?