sentence: The difference between the Short-beaked Common Dolphin and the Long-beaked Common Dolphin, is that the Short-beaked Common Dolphin is smaller in size and has a smaller beak than the Long-beaked Common Dolphin.
modified: fix grammar: The difference between the Short-beaked Common Dolphin and the Long-beaked Common Dolphin, are that the Short-beaked Common Dolphin were smallest in size and has a smallest beak than the Long-beaked Common Dolphin.