The number of elements of 7.2 formed by the digits 0 and 5.

To form the greatest number, arrange the given digits in descending order.
The digits are 7, 2, 0, 5.
Arranging them in descending order gives: 7, 5, 2, 0.
The greatest number is $7520$

To form the smallest number, arrange the given digits in ascending order. However, a number cannot start with zero if it is a four-digit number. Therefore, place the smallest non-zero digit first, followed by zero, and then the remaining digits in ascending order.
The digits are 7, 2, 0, 5.
The smallest non-zero digit is 2.
Arranging them to form the smallest number gives: 2, 0, 5, 7.
The smallest number is $2057$

Subtract the smallest number from the greatest number.

The difference between the greatest and smallest numbers is $\text{5463}$.