what is same in crop image and original image in C#?

If you mean that you need to compare two copies of the same image and see if there are any differences between them, the details depend on the compression criteria you want to apply (size, color, etc.).
For example, you can use a programming toolkit that supports loading different type of images and provides image processing functions to help you with the comparison part.

See the following article from LEADTOOLS that provides sample Compare Images project.
https://www.leadtools.com/blog/imaging/image-processing/compare-images-25-projects-25-days/#prettyPhoto