Confusion: MS or MSN?

After looking at some nurse anesthetist schools' websites, I've noticed some say that in the end of the program, students will have either a MS or a MSN. What is the difference?
Fore example, I live in Wisconsin and the crna program at UW Lacrosse (the only anesthetist program in Wisconsin) said something on their website about "further" steps to get the "MS" degree. I'm really confused.
I thought that when you complete any nurse anesthetist program you automatically have received some type of Master's degree?
When applying to these programs, should one ask the director of the program which degree will be conferred?
What is the difference (if there is one) between the crna that has an MS or MSN (as far as scope of practice, compensation etc.)?