1. A computer readable recording medium storing a difference emphasizing program executed by a computer, the program comprising: a superimposing procedure of aligning a first three-dimensional model and a second three-dimensional model in orientation and position in accordance with a predetermined rule, and storing, in a storage device, data of respective apices of the first three-dimensional model and the second three-dimensional model having been aligned in orientation and position; a finding procedure of, based on the data stored in the storage device, finding a corresponding point on the first three-dimensional model, which corresponds to the apex of the second three-dimensional model in a direction of a particular axis; a difference calculating procedure of, when the corresponding point is detected in the finding procedure, calculating a difference between the first three-dimensional model and the second three-dimensional model in the direction of the particular axis based on the corresponding point and the apex of the second three-dimensional model, and storing the calculated difference in the storage device; and an enlarging procedure of enlarging the difference stored in the storage device in the direction of the particular axis, calculating a position of the apex of the second three-dimensional model after the enlargement, and storing the calculated position in the storage device.