Espionage is a term closely associated with spying. It implies the systematic use of agents or spies to procure information generally about another country's politics or military. It is therefore the art or practice of procuring confidential information or secrets from any rival or enemy that may be used to gain some king of economic, political or military advantage. It is generally considered to be some kind of collective effort like that of a corporate or a government.
A spy or an agent is the label given to a person employed for the specific purpose of covertly obtaining information. The information id gathered without the knowledge of the source and ideally all tracks must be covered so that there is no incriminating evidence left behind. A spy may be a mole or a person that is hired prior to them obtaining secrets or a defector who is hired after he/she has gained access to the information needed.
A spy or an agent is the label given to a person employed for the specific purpose of covertly obtaining information. The information id gathered without the knowledge of the source and ideally all tracks must be covered so that there is no incriminating evidence left behind. A spy may be a mole or a person that is hired prior to them obtaining secrets or a defector who is hired after he/she has gained access to the information needed.