In volleyball, when is a set made up of 25 points and when is it made up of 15 points?

Question

And yes, I mean in the same event.

Answer 1

The first 4 sets are made up of 25 points and the 5th and final set is made up of 15 points.

Answer 2

the first 4 sets is made up of 25 points (a team needs to win 3 sets to win the match), BUT if there is a tie (2sets-2sets) there'll be a fifth set made up of 15 points to decide who wins the match.

Answer 3

In the first 4 sets the game is played to 25 points. But in the event of a tie (2 sets-2 sets) the next set is played to 15 to decide the winner.