If you think your particular troubles are too heavy and too traumatic to laugh about, remember that laughing is like changing a baby's diaper. It doesn't solve any problems permanently, but it makes things more acceptable for a while. - Barbara Johnson
Yes, they really are exactly the same length. We expect pictures to represent objects which are square or made up of right angles. In this optical illusion, the eye computes the distance as though both boxes were square, which would support the conclusion that the one line is shorter since its box is only half the size of the other.