A category is an area that you assign a particular post to. They are used to organize your broad topics and information in a logical, hierarchy way. The organizing system allows users to find and retrieve information quickly, add sub categories if they choose. For example, one might want to use categories such as fiction and non-fiction. Then they might want to narrow the focus into subcategories such as science fiction, mystery, cooking, and medicine.
A tag is specific keyword used in a post that describes it in a more detailed way. So if you are looking for a post about mysteries, look for mystery tags such as mystery, sleuths, thrillers, etc.

My plan in this blog is to use categories such as general, corvid behavior, habitat, species, and reproduction. Some tags that I might use are learning, mating, feeding and arizona.