What SW said.
Also load data for a specific powder may state for example 5.0 to 6.1 grains. A recipe will state an exact grain such as 5.6. A specific bullet weight, such as 230 grains. Primers come in either standard or magnum and the "recipe" will state which one to use. Let us not forget over-all length (OAL) which also varies and will be stated in the recipe.
Someone has taken the time and trouble to experiment and find out what combination of these components works best in a particular gun.
Good example is that the 9mm reloads I developed a recipe for worked great in my C9 but performed terrible in my 995. I knew Silicon Wolverine had a great 9mm carbine recipe. I asked, he shared, and saved me a lot of powder, primers, and lead working something up. So now I have 2 recipes for 9mm that use different powders and OAL but the same boolit weight.