What is the difference between a Master of Science (MS) degree and (MSc) degree?

There's no practical difference between an MS (Master of Science) and an MSc (Master of Science) degree. They are essentially the same thing. The difference is purely in the abbreviation used by the awarding institution. Some universities use "MS," others use "MSc," and it's largely a matter of convention or preference. Both denote a postgraduate degree in a scientific or technical field.