Image and Image Pro have virtually identical feature sets, but are really different products which is entirely the result of the fact that Image Pro is a certified visual. Let's learn more.
Both Image and Image Pro are designed to display images based on a view or filter within your data set. However, Image Pro is certified by Microsoft, which means that Microsoft has reviewed it's source code.
This sounds good! But one aspect of certified visuals is that they can't access any remote data sources, due to Microsoft's security policy. So, for example, if you have an image file that is stored on a cloud store like Amazon or Azure, this is a remote data source. You access the image via a URL, and this is prohibited in certified visuals due to Microsoft's security policy.
So, how do you display images in Image Pro? You have to ensure that they are stored entirely within your data set. You do this by serializing the image to Base64 text. And then when a user wants to display the image, it is deserialized and displayed. This takes a little more effort that simply storing the images somewhere and accessing them via a URL. It also limits the size of the images you can display (about 1.6 mb max).
Let's say that you aren't willing to store your images within your data set and you're ok with accessing remote data. So Image seems like the best fit. Well, one thing you should know is that based on Microsoft's policy, on certified visuals can export to PDF or PPT files. If exporting is important to you, then Image Pro is something you'll have to consider.
These differences are unfortunate, but are part of the landscape in the Power BI world. They apply to every other certified visual, but the differences are particularly obvious for Image and Image Pro because of their reliance on images.