All grape juice made into wine is initially white. Reds are steeped with the red skins for an extended period of time, extracting the color and other compounds (tannins, etc.)

In a recipe, wine is typically used for its acidity and flavor. Substituting red for white will typically provide much of the acidity, along with color. What you typically don't want in a white wine recipe that may be a problem are the tannins and any strong oak/wood flavor, which could become harsh and bitter in a white wine recipe, which is typically lighter. The oak/wood issue is why many "California-style" heavily oaked Chardonnays are not great for cooking. (Also the secondary malolactic fermentation reduces the apparent acidity of the wine).

That said, there may be many cases where these qualities would not be a problem. There are certainly many light red wines with limited tannins and oak for which you could make an interesting substitution.