LPS, or Large Polyp Scleractinian or Large Polyp "Stony" are corals typically found in shallow water lagoons. Examples are Frogspawn, Hammer, Anchor, Bubble etc...
SPS, or Small Polyp Scleractinian corals include the genera Acropora, Pocillopora, Porites etc. They are typically found in turbulent, nutrient poor areas of the reef. They require intense light for the best growth...
Matt