Question

birds and mammals one difference

Answer 1

mammals give birth to young ones where as birds lay eggs for their young ones

Answer 2

The differences between mammals and birds, the first thing that comes to mind is that mammals give birth to their young whereas birds lay eggs.

Now let us look at other differences between mammals and birds. The birds have feathers whereas mammals have only fur or hair. This feature is one of the main features of birds that differentiate them from mammals. Birds use feathers for controlling body temperature, flying, and attracting the opposite sex.
As birds need to fly, they have porous or hollow bones. In contrast, mammals have denser bones. Birds have wings although mammals have paws, hands, and hooves.