Kanclerz was one of the highest officials of the state in old-time Poland.
He leds the foreign policy of the state and was responsible for the chancellery of the King or the court princes.
Since the 14th century the office of "Kanclerz krakowski" (Chancellor of Kraków) changed in "Kanclerz koronny" (Chancellor of the Crown). Since then he became responsible for the whole Kingdom.
After the Union of Lublin in 1569 the office was doubled and got a subtitute, the "Podkanclerzy".
Kanclerz krakowski - Chancellor of Kraków
Kanclerz koronny - Chancellor of the Crown
Kanclerz wielki koronny - Great Chancellor of the Crown
Kanclerz wielki litewski - Great Chancellor of Lithuania
Podkanclerzy koronny - Deputy Chancellor of the Crown
Podkanclerzy litewski - Deputy Chancellor of Lithuania
The DeputyChancellor was however not a subordinate of the Chancellor and his independence was specifically confirmed by the laws passed during the reign of the king Alexander the Jagiellonian.
Chancellor and the DeputyChancellor (who was not a direct subordinate of the chancellor) were responsible for the work of their chancelleries, respectively Greater and Minor one.
Due to their important power the Chancellors were considered the guardians of the king and country, making sure the kings folly would not endanger the country by forcing it into an unnecessary war (among the wars prevented by the chancellors was the great crusade against the Ottoman Empire planned by Wladyslaw IV Waza in 1630s).
The office as chancellor (Royal Chancellor) seems to have appeared in the 12th century and until 1660 it was the title of the leader of the state administration (a kind of a “Home Office” but often with foreign political duties).
Chancellor of the Exchequer, the minister with overall responsibility for the Exchequer or Treasury.
In reality, the post of Chancellor of the Duchy of Lancaster, effectively like a chairman of trustees, carries minimal work and responsibilities, so it is used in effect as a Minister without Portfolio position, often given to the chairman of the party in power to give him or her a seat in cabinet.