There are many different types of nails. The grading system can be confusing and the many different types of coating and head styles to go with them just add to the confusion. This list is by no means exhaustive and will be updated from time to time. The sizes are graded in a system that refers to their size. The larger the number, the larger the nail.
Common nails have larger heads that are clearly visible after the nail has been driven.
They are used for framing buildings and situations where appearance is not important. Finish nails have a much smaller head that can be concealed after the nail has been driven. These nails are used for applying trim and other areas where appearance is important. Roofing nails have a large head that are intended to hold shingles and are usually galvanized. Drywall nails look the same as roofing nails but are not galvanized.