The BJCP Style Guidelines use some specific terms with specialized meaning: “Category”, “Subcategory” and “Style.” When thinking of beer, mead and cider styles, the subcategory is the most important label—“subcategory” means essentially the same thing as “style” and identifies the major characteristic of one type of beer, mead or cider. The larger “categories” are arbitrary groupings of beers, meads or ciders, usually with similar character but some subcategories are not necessarily related to others within the same category. The purpose of the structure within the BJCP Style Guidelines is to group styles of beer, mead and cider for competition purposes; do not attempt to derive additional meaning from these groupings.
The term “Sub-style” was used in the BJCP Exam Study Guide in the past as a synonym for Subcategory, but this phrase is no longer used in current reference materials. If you see the phrase used, substitute either “Style” or “Subcategory” as appropriate.