Sometimes recipe will make it pretty obvious what style it is. But the very best way to determine which style to enter in a competition, or just when handing it to a beer snob.. Is to poor a sample and compare what you see, smell, and taste, to the style guidelines. Some styles are (controversial) very similar to others. For example, in the glass, a certain pale ale might actually line up better to IPA guidelines. Or a beer with some vegetable in the recipe might not be present in the glass. There are numerous examples where a slight bump can move a beer from one style to another.