What's the difference? Will brads be enough for basic molding, crown molding and finish work?

Brads are a finer gage then finish nails. I will use a combination of both when I get to the trim stage.

yes brads will be just fine...like the guy above said they are just a smaller version of a finish nail...hence the brads make smaller holes and are slightly easier to fill with wood putty

Be sure to use the 2 3/4" ones for the crown molding.

I have found my 18g finish nailer to be my most versatile nailer. Just big enough for most moldings IE crown, chair rails, base boards. And just small enough that it doesnt split the small moldings in my finish work. Not that I couldnt use larger or smaller gauges for each of those examples, its just that I always seem to grab that gun first, because I know it will work and I can easily switch nail lengths depending on what Im driving into.

cool. i think i am going to go with a brad nailer and see if that will do the trick for me. When i build the fabric frames they are going to be pretty thin so i worry i may split the wood

I use a brad nailer since I don't have a finish nailer. I have had great success with all types of mouldings especially crown. I use my crown stapler for panels.