A comparison of the option available in the "adjust image" window. The help file says:
Display Format
PhotoStitch supports the following two display formats for the merge results. Display the merged image in both formats to decide which one you prefer. The choice of formats is only available when [Panning (Scenery, etc.)] is selected in the Merge Settings window.

Normal

This format is for displaying images that have a broad perspective. It is appropriate for viewing an image that has been merged from a large number of images. However, objects with straight lines, such as buildings, will appear rounded.

Wide

This format displays buildings and other objects with straight lines without distortion or bending. It is best suited to subjects with many prominent straight lines. However, the field of view that can be encompassed in this format is limited. Parts of large merged images may extend beyond the area shown by this format.

To change the display format:

Click the [Adjust Image] button in Step 3 to open the Adjust Image window.

Select [Normal] or [Wide] from the Display Format section.

Click the [Apply] button in the Display Format section.

Click the [Close] button to close the Adjust Image window.