Distinguish between Final Goods and Intermediate Goods.

Final goods refer to those goods which are used either for final consumption or for investment purposes. Whereas Intermediate goods refer to those goods which are used either for resale or for further production purposes. 

Or 

Positive externalities refer to benefits caused by one entity to another, without being paid for it. Whereas Negative externalities refer to the harms caused by one entity to another without being penalized for it.