Duchy and Electorate of Saxony during the Schmalkaldic War

Question

The Wikipedia page for the Schmalkaldic War list the Duchy of Saxony and the Electorate of Saxony as opposing sides of the war, each with their own monarch (Maurice is the Duke of Saxony, John Frederick I is the Elector). From reading the rest of the page, looks like John Frederick I is the main leader of Saxony. What was the Duchy of Saxony then? Was it a subordinate territory to the Electorate? Or was it a different land, ruled independently from the Electorate? Or was it just a title, like the "Prince of Wales" in the UK does not really rule Wales? How did it come to be separate from the Electorate?

Another curious thing is that in the succession box below their articles, Wikipedia claims that after the Elector's defeat, they exchanged their title (Maurice became Elector, JF became Duke). Why did they grant the Duke title to the defeated Elector?

Answer 1

In 1485 the House of Wettin split into the Ernestine and Albertine branches, splitting Saxony between them. During the Schmalkaldic War the two branches were headed by John Frederick I and Maurice, respectively Elector of Saxony (Ernestine) and Duke of Saxony (Albertine). The normal distinction between the two sovereignties was made through distinguishing the Electorate of Saxony from the Dukedom of Saxony, and not through the name of the ruling family branch.

In the aftermath of the war:

The captured Elector John Frederick I at first was sentenced to death, and, in order to obtain pardon, on 19 May 1547 signed the Capitulation of Wittenberg.2 He lost the electoral dignity and some minor Ernestine territories to his cousin Maurice, who was declared the new Saxon Elector on 4 June.

The Ernestine branch ruled Thuringia, under an increasing number of progressively smaller and more intertwined independent princedoms as the line splintered, while the senior line of the Albertine branch ruled what would become the Kingdom of Saxony under Napoleon.