Discovery = the process of finding information , a place or an object for the first time.(something that is already existing)

• The timely intervention of the police led to the discovery of the stolen jewellery.
• The discovery of oil made many gulf countries rich.
• The discovery of the body helped the police to sort out the complicity of the accused.

Invention = creation, development, introduction etc.( something that is not already existing).

• The invention of radio revolutionised the dissemination of news and information.
• The invention of new devices in agriculture increased the agricultural productivity.
• The invention of printing technology made a major breakthrough in the educational field.
• The invention of computers made rapid growth of information technology that led to what is called information explosion.