How is a mammal?

A crocodile is a reptile, not a mammal.

There are two things which will tell you if an animal is a mammal or not.1. All mammals make milk to feed their their young. Only mammals do this. Don't be fooled by breasts and nipples. Some mammals...

They mean the same thing it is just that mammals is the plural form of mammal.

Marine mammals are divided between the orders Cetacea, Sirenia, and Carnivora. Whales, dolphins, and porpoises are in the order Cetacea. Manatees and dugongs are in the order Sirenia. Seals, sea...

mammals can give birth to live young they have hair on their bodies and they can produce milk.