SLA or Steroelithography: The rapid prototyping technology of SLA or stereolithography provides with the greatest accuracy and gives the best possible surface finish among all the rapid prototyping technologies. This technology uses liquid photopolymer resin that has the property of solidifying on contact with the correct color light. The most commonly used photopolymer materials need UV light, but resins that work in visible light are also used.
SLS or Selective Laser Sintering: SLS or Selective Laser Sintering rapid prototyping technology uses metallic powders or thermoplastics. This technology is quite similar to stereolithography. The finishing time is reduced as the undercuts and overhangs are given support by the solid bed of powder. The surface finishes are not as good as stereolithography. It requires no final curing like SLA, but the object is porous as it is sintered. The mechanical characteristics of the object can be improved by infiltrating the object with some other material as required by the application. This method is used in direct fabrication of ceramic and metal tools and objects.”