That is a good question! I think that when you are living in "survivalist" mode, you might automatically be living a frugal lifestyle by default. It is just part of it. However, the same might not necessarily be true for the "frugal" person. Many people that are doing just fine in life financially speaking, are also very frugal. It might be part of the reason why they are doing so good financially.
So, I think there is a small difference for those reasons. If a person has ever had to survive, they will surely know how to be frugal. I can remember my mother saying once, "I remember being amazed at how little one can live on, when you need to." That is so true I think.