What's the difference?
They say that sales in cardboard boxes should be a sign of rejuvenation.
They say that sales of cardboard boxes should be a sign of rejuvenation.

What's the difference?
Thanks a lot.

Question

What's the difference?
They say that sales in cardboard boxes should be a sign of rejuvenation.
They say that sales of cardboard boxes should be a sign of rejuvenation.

What's the difference?
Thanks a lot.

Answer

“Sales of cardboard boxes” is the idiomatically correct way to talk about cardboard boxes being sold.  “Sales in cardboard boxes” sounds like a sale is somehow happening inside of a cardboard box.