Does not matter vs. Makes no difference
For most Americans, choosing between these phrases is six of one, half a dozen of the other! Completely synonymous -- you can flip a coin to pick the right one.
But there's actually a major difference in meaning between them.
Will I die at 30, or 80?
Does not matter. At least in the big picture, what's BY FAR THE MOST important is to remember what life is about: dying in the state of grace and saving our immortal souls.
But does it make no difference? NO WAY!
It makes a huge difference how long I live: how much impact I have on the world, on the lives of my children, if I even have any children, how much merit I can gain for heaven, etc.
See the difference between these two seemingly synonymous phrases?