Answer:
What is the difference between a poorly dressed man on a bike, and a well-dressed man on a unicycle?
I build bridges of silver and crowns of gold. What am I?
Break me and I am better immediately set and harder to be broken again.
I cannot be bought, cannot be sold, even if I'm sometimes made of gold. What am I?
I bring light to a dark world. In a current I travel and through tunnels I am hurled. Touch me and I'll kill you. What am I?
The answer I give is yes, but what I mean is no. What was the question?