liveness

What is the difference between a liveness and a progress property?

Hi all.. I know this is a very academic question, but I was hoping someone here could help me get an answer. I'm taking a concurrency class in which we use LTS'es and FLTL's. In one of our assignments a question is given: "Give an example of a liveness property, expressed as an FLTL formula, that cannot be expressed as a progress prope...