Inspiration is the process of inhalation or intake of the air.
It is by inspiration that oxygen enters the body.
It takes place by contraction of diaphragm and intercostals muscles. (Internal and external intercostals muscles)
It is an active process.
Expiration is the process exhalation or breathing out the air.
It is by expiration that carbon-di-oxide is expelled out of the body.
It takes place by elastic recoil of the diaphragm and relaxation of intercostals muscles.
It is a passive process.