meaning - What is the difference between a company, organisation, industry, firm, corporation and business?

A company is any form of business whether it is small or large.
Generally the term "company" indicates a particular kind of business dealing in a specific product.

An organisation is the larger form and generally comprises of a
number of companies. Simply, a company is an organization, but an organization is not just a company.

An industry is the combination of companies in same line of
business.

Firm, corporation and business are synonyms of "company".

An Agency is a particular kind of company, which serves as an intermediary between clients (other companies or individuals).

Is this correct?

Answer

They are all related but in different categories.

This is how they are related:

• Industry
  
  
  
  • Organisation
    
    
    
    
    • Company; Profit Organisation ("Business")
      
      
      
      • Corporation ("Co.")
      
      
      
      
      • Public Limited ("Ltd")
      
      
      • Private Limited ("Pte Ltd")
      
      
      • Incorporated ("Inc.")
      
      
      • Trust company
      
      
      • Agency
      
      
      
      
      
      
      
    
    
    • Firm
      
      
      
      • Partnership
      
      
      • Limited Liability Company ("LLC")
      
      
      • Limited Liability Partnership ("LLP")
      
      
      
      
    
    
    
    
    
  
  
  • Non-profit
    
    
    
    • Charity
    
    
    • Foundation
    
    
    
    
  
  
  
  

Disclaimer: The chart above is incomplete as it is just to let the OP to have the image of how they are related.

Disclaimer 2: I am unsure whether Industry includes Non-profit. I don't think so, I think it includes categories of businesses like Automobile, Telephone, Internet, etc.

The most common mistake people make is the usage of Company, Corporation and Firm.