The brad nailer is a not a standard finish nailer and is usually used for affixing small moldings and trim to a woodworking or finishing project. Because brads are thinner than finish nails, they can often be used in instances where a typical finish nailer might split the piece of trim.
If you are affixing crown molding or trim to drywall you probably want to use a finish nailer.
At Equipment World we have the compressed air brad nailers.
Here are some great reference videos: