Probably the best way to answer this question is with a meme. :)
One notable difference between working hard and working smart is the time and effort one consumes to get the desired result. Working Smart focuses on finding an efficient method to get the result fast without taking too much effort while Working Hard focuses entirely on the end result.
A good classic example for this would be transporting a heavy block like the one in the image above. People who choose to Work Hard would probably lift the heavy block as it is the most common way to transport a block. The most common way but not the most efficient way. People who choose to Work Smart would first get a cart or something to put the heavy block first for easy transport, making the effort and time consumed by the worker very little allowing him to transport more blocks compared to the Hard Working one.
So yeah I choose to Work Smart.