Question

Write the difference between silk and cotton fibres

Answer 1

is that cotton is a plant that encases its seed in a thin fiber that is harvested and used as a fabric or cloth while silk is (uncountable) a fine fiber excreted by the silkworm or other arthropod (such as a spider).  

is that cotton is made of cotton while silk is made of. 

cotton is to get on with someone or something; to have a good relationship with someone.