Let's review the terminology. A product is what you get when you multiply two numbers. So, the product of 5 and 2 is basically "52," and the product of 5 and 1 is "51."
The difference means when you subtract one from the other. So, the difference of 52 and 51 means "(52)-(51)". (Note: I put in parentheses to make sure the reader understands that 52 is separate from 51. 52-51 is confusing: you might not know what to do first!)
So, "(52)-(51)" can be your answer, OR you can simplify it further by actually doing the multiplication: "10-5". If you want the answer, just subtract--the expression is equal to 5.
Answer: "(52)-(51)" OR "10-5" OR "5"
