I did a quick search on google and, not only I see both versions, I even see both of them in the same document.

Example: Region-Enhancing Network for Semantic Segmentation of Remote-Sensing Imagery - PMC

the dataset with much more images
the dataset with many more images

Specific searches show these numbers:

• About 4,520,000 results for “much more images”
• About 2,780,000 results for “many more images”

Is there any difference between them?
Thanks!