Lets say there are two builds in the software development and take an example of a single screen. Lets say In the version-1, there are two text fields and in version-2 there are 4 text fields.
But there may be chance of alignment or layout issue due to the addition of new text fields in version-2.
So if we are able to findout the elements from images then we can compare their positions and pixels.
So at any point of time if there is any layout or alignment issue comes up (by comparing the same element height, width and pixels) then just take the screen shot of this.
If anyone having any other solutions for this , then please feel free to share.