Crocodiles and alligators are very similar to amphibians but hey are not termed under amphibians. In fact they are a part of the reptile family. They are the larger reptiles in this family. The difference between amphibians and reptiles are that though many reptiles like crocodiles and alligators can live in both water and land they are less dependant on water than the amphibians. An amphibian might be able to live on land but it needs a water body nearby. It cannot survive on dry and desert areas unlike the reptiles.
Moreover though crocodiles and alligators can live in water they have to come on the land to lay eggs which is not mandatory in the case of amphibians like frogs. The reptiles like crocodiles, alligators and other species related to them breathe through their lungs while amphibians have other organs to fulfil this purpose. Thus the crocodiles are not a part of the amphibian family because they are more closely related to the reptiles with their scaly skin, lizard like shape, and jaws.
Moreover though crocodiles and alligators can live in water they have to come on the land to lay eggs which is not mandatory in the case of amphibians like frogs. The reptiles like crocodiles, alligators and other species related to them breathe through their lungs while amphibians have other organs to fulfil this purpose. Thus the crocodiles are not a part of the amphibian family because they are more closely related to the reptiles with their scaly skin, lizard like shape, and jaws.