Public Sector i.e. Government. 
E.g. collect taxes, police, welfare, roads, military, 
building inspections, schools  (local) 
All citizens control govt. thru voting in democracies and all may benefit collectively. 

Private For-Profit Business Sector.
Owners keep profits & losses minus tax.
Vast wealth created in aggregate.  
Subject to government regulations.
Includes income from contracts with govt. agencies

Plural, Private Nonprofit
 Aiming to serve a community need thru service and/or advocacy in health, education, welfare, arts, religion, political causes, etc. 
Founders & funders decide who benefits.

Mutual Benefit.
"Members Only" control & enjoy benefits.





Relations Between Sectors

Public Sector can regulate Business  
BUT
Business lobbies regulators and its cash influences elections to favor anti-regulation parties and to shift public opinion against active government role.  This has greatly increased, shifting the balance (UNbalance ?) between these two sectors.

Within the Plural (Third) Sector many organizations are active on both sides of the Regulation Issue and in efforts to tackle (or deny) Climate Change. 
Free speech reigns in this sector, essential to democracy and liberty. 

Stronger Public Sector and Plural (3rd) Sector could reduce problems of IMBALANCE

Ref.: mintzberg.org