Classify industries on the basis of their main role. How are they different from each other?

According to their main role :
(i) Basic or key industries which supply their products or raw materials to manufacture other goods e.g. Iron and steel and copper smelting, aluminum smelting.
(ii) Consumer industries that produce goods for direct use by consumers–sugar, toothpaste, paper, sewing machines, fans etc.

According to their main role the industries are classified as: 

• Basic or key industries. These industries supply their raw materials to manufacture other goods, e.g., iron and steel, copper smelting etc. 
• Consumer industries. These industries produce goods for direct consumption by consumers, e.g., sugar, fans paper, toothpaste, etc.