Occasionally it'll happen that the entire orchestra stops playing for a couple of seconds. They're not taking a break - at least, not one that they've decided to insert into the piece. A combination of two or more different melodies that still sound good together is called the counterpoint. Like Row, Row, Row Your Boat sung by you and the Three Tenors, each person starting from a different point in the song. Music composition Cadenza .
Some movements end with a cadenza, which is a solo.
When the orchestra stops playing, a soloist keeps going and shows off for some time ranging from a few seconds to a few minutes. These are the different sections in a whole classical piece. Most symphonies have four movements and most concertos have three. Movements of a piece often sound unlike each other, but they are related. When a piece is played, there is usually a pause between movements.