AvesMammalsIn aves, body is covered withIn mammals, body is covered with hairs. They do not havefeathers and they possess a beakfeathers and the beak is also absentMammary glands are absent in aves.Mammary glands are present in mammals. Some of them layThey lay eggs. Hence, they areeggs and some give birth to young ones. Hence, they are bothoviparousoviparous and viviparous