Two choruses. First time through, you hear the first one. Second time, you hear both, as though it was one long chorus. In placing them together, they create liaison between the two by a vocal harmony part (not heard in the first utterance of chorus number one) that comes in at the end of the first and continues in the second.
After this, the instrumental break. Violin (or maybe fake violin) and what sounds like some reed organ.
Third time through, you get both choruses once again. The second chorus is self-sufficient, though, and it's this one that repeats for the closing.