What is the difference between air and atmosphere ?

Atmosphere is a blanket of gases and layers surrounding the Earth.  It protects us from the harmful rays and scorching heat of the sun it consists of a number of gases, dust and water vapour. the changes in the atmosphere produce changes in the whether and climate.

Air is a homogeneous mixture of more than one type of gases in which  gases are completely mixed with each other. It contains oxygen, nitrogen, carbon dioxide etc