Images resizing after upload

You are talking about a responsive project, which probably is created with Fluid Boxes? I cannot see a difference between both images, sorry, my bad. All depends on the setup of the image and the fluid box it has been embedded in. Could you offer some details about that? Did you view the uploaded output with the same browser and on the same system while keeping all settings as compared to the Preview local testing?

We need more information about this project if you expect any solutions. The screenshots you've attached don't convey much information about the problem (because they are cropped). I would start by telling us what version of Adobe Captivate you are running. For example, I'm running 11.5.5.533. Click on the Help dropdown menu and select About Adobe Captivate to get this information. Also, knowing what type of project you have created would be helpful. For example, blank projects, responsive designs, VR projects, etc.