What's the difference between shipping agency, ship agency and shipping management?

What's the difference between the following: 

a.) ship agency 

b.) shipping agency 

c.) shipping management

Ship agency could be an agent for the ship itself in a specific port (AKA husbandary agent). 

Shipping agent is usually an agent for cargo bookings (acting either for the vessel owner or as a broker to export and import specific cargoes). 
If it is a port agent, it is specific to a location (or country) but it could be an agent for all 
cargoes from a particular exporter. 


Shipping management is a much broader term. 


If you mean Ship Management, that is the operational management of the vessel (usually by a third party on behalf of an owner) to make sure the vessel is properly crewed, 
victualled, bunkered, maintained, insured, carries all approprate certificates and inspections, etc. 


Shipping management can also mean the entire management team of a shipping company (CEO, CFO, COO, etc) who run the company to manage it profitably.