What is the difference between share and stock ?

I've seen this exactly worded question on here recently, making me wonder if this is a homework question.

Stock is the initial investment in the corporation. i.e. I buy stock in the company, and therefore have ownership in it. A share is how the stock is divided up. For instance, a company could have 500,000 shares of stock. So the stock is like the thing you have, and the shares is the individual units of it. So I might buy 1000 shares of that stock.