Brad nails are formed from fine 18 gauge wire , which means they are smaller in diameter and typically have less holding strength.The benefit to an 18 gauge brad is its size. Brad nails are easier to conceal in small pieces of wood trim. Their size also helps prevent surface splitting, which could occur if the fastener is too large for the material it is being nailed into. The downside to a brad is its holding power.

Finish nails are made from heavier 15 or 16 gauge wire, which means they can handle a greater payload. For larger trim , such as baseboards or crown molding, a finish nail is more suitable. in all,the finish nail offers increased support and withdrawal resistance.