Mammals and reptiles are the two major classes of phylum Chordata. Reptiles were first among true terrestrial vertebrates. Both have inhabited the earth for millions of years. Mammals and reptiles both are tetrapods and have almost same organs.
Mammals are those vertebrates which give birth to live young, however, some egg laying mammals are also found e.g. duckbill platypus.The young ones are not able to get food on their own and need nourishment in the form of milk from the mammary glands of their mother. They have fur or hair on their bodies and also have sweat glands. They can regulate their body heat.
Reptiles are mostly egg-laying vertebrates, however, some of them also give birth to live young e.g. viper snakes. Their eggs have hard-shell which protects the embryos. Most reptiles are carnivores but have a very slow metabolic rate.
Difference between Mammals and Reptiles
The main difference between mammals and reptiles is the way of regulation of body heat. Mammals can regulate their body heat while reptiles cannot. They need an external heat source such as the sun. Mammals have furs on their bodies while reptiles have scales. The newborns of mammals need milk from their mothers while those of reptiles fend for themselves. Reptiles are cold-blooded animals while mammals are warm blooded. The growth of mammals is limited after adulthood while in the case of reptiles growth continues throughout life.