"...and for up to half of the flour in a recipe using entirely all-purpose."
"For a baked good that tastes similar to one made with white flour, add half white spelt flour and half whole-grain spelt flour. Whole-grain spelt flour is typically labelled "spelt flour," whereas white spelt flour is labeled "white spelt flour." White spelt flour contributes to a more refined, less nutty, flavor.
"Just like wheat flours, spelt flour comes in two varieties; whole or white spelt. White spelt flour has had the bran and germ removed. It will give you a lighter texture in baked goods and works well as a substitute in recipes that call for all purpose flour. Whole spelt flour is close in texture to whole wheat flour.
Because spelt is more water-soluble than wheat, it is often recommended to use three quarters the amount of liquid in a recipe when making substitutions for wheat flour. I have found that this varies depending on the particular batch of spelt flour and the recipe. I will usually start with a bit less liquid than called for in the recipe and add more if needed to create the appropriate consistency.
This is kind of confusing, everyone is different.. try each and see which one works best for you
Credit @ Thekitchn
Credit @ whatsCookingAmerica