The absolute value of a negative number is equal to its inverse, for example, the absolute value of -2 is 2.
The opposite number means that the absolute values of two numbers are the same, but the signs are different, so the two numbers are opposite, for example, 2 and -2 are opposite.
So the inverse of a number is opposite to its sign, the inverse of 2 is -2, and the inverse of -2 is 2.
But the absolute value of a number is not necessarily the opposite of itself. The absolute value of 2 is 2.