The heavier gauge (lower number) means that the metal is thicker. It should be harder to dent if you dropped something. Scratches...that would depend on the alloy - not all SS alloys are the same. It takes a lot more work to bend heavier gauge metal into the desired shape, but it also means that there's more metal thickness where it gets stretched most therefore it's stronger. A deep sink may require heavier gauge so there's enough metal once it is shaped. A heavier gauge sink may end up being quieter (won't ring as much) when used with a garbage disposer.