I think the difference is that what that blood test will give you is an indication as to your current situation. Are there elements that are out of whack in your blood count? I'm really going beyond my ken here, but they'll assess your current state and they also have access to what's happened in the past. A genetic test is a predictor, with a greater or lesser accuracy, about what might happen in the future. That's the difference.
On November 15th, 2016. See this statement in context.