The difference is very simple: you use steel swords to kill humans and animals while using silver only on monsters and freaks of nature. (gameluster.com)
Finally, as for the sound effects, they are pretty solid, from the sounds of steel swords clanging, bodies being sliced into two, to the more simple things such as clay vases breaking or a water stream running though the level. (cogconnected.com)
The lesson: how the craftsmen used the secrets of metallurgy to turn iron ore into the final product — an ultra-sharp, slightly curved steel sword. (technologyreview.com)