Unfortunately, that is not really the case yet. Some 3D printers say you can print in metal but what they are really using is the same plastic with metal dust sprinkled in. So while it looks like metal it does not really have the properties you really want in metal, such as strength.
Most of the different materials that 3D printers offer are pretty much the same plastic modified in some way.
You're probably thinking of SLS, which is nylon based, but can have stuff sprinkled in. The metal printers that ProMetal makes bind steel powder together, and then infuse it with bronze. It's quite strong, and I've heard that the grain structure is actually better than casting.
Most of the different materials that 3D printers offer are pretty much the same plastic modified in some way.