Reptiles have scales or scutes on their skin and claws on their feet; meanwhile, amphibians have moist, smooth or warty skin that lacks scales. Amphibian feet also lack claws. Reptiles lay eggs with leathery shells or can give birth to live young. Amphibians have shell-less eggs that need to be laid in a watery or moist environment to protect them.
Both adult and juvenile reptiles breathe by means of lungs, and the young are basically replicas of their parents. Amphibians go through a larval stage where their young may resemble fish and breathe with gills. As the larva grows, it slowly grows legs, loses its gills and acquires lungs. Still, it must stay close to a water source to keep its skin from drying out and for breeding. In the case of frogs and toads, the digestive systems of the adult and the tadpole are also different. Frogs and toads are largely carnivorous, while tadpoles eat vegetation.
There are a few exceptions to the rules, however. Leatherback turtles lack claws on their feet and have few scales. A handful of species of frog give birth to live young, and at least one type of salamander, the axolotl, retains its gills all of its life. Some salamanders bypass the larval stage.