Answer:
The difference can be elaborated by the following equation
"4 times the sum of x and y"

and "sum of 4 times x and y"

Explanation:
In the first condition the two terms x and y are summed up first then multiplied by 4. First add two digits then multiplexed..
In second case the 4 times of x is first calculated then added with y.
Note:
First condition will always be greater than second because in first condition both the digits are multiplied with 4 but in second only second is multiplied with 4.