What are the differences between Urgent Care Centers and Emergency departments?

What are the differences between Urgent Care Centers and Emergency departments?
What is the best setting to treat the following conditions (choose between primary care clinic, urgent care center, and emergency room)?
a.A 24-year-old male with a sore throat, cough, without fever, wheezing, rash or other constitutional symptoms.
b.A 46-year-old female who twisted her ankle and now has some swelling and bruising around the inner aspect of her ankle.
c.A 68-year-old male with a one-hour history of severe chest pain, accompanied by sweating, palpitations, and a sensation that he is going to pass out.
Prepare a written 2-page discussion (double-spaced).
As you are completing this assignment, think about how you can apply these skills to your career.