Showing Of 'features' Under Images

I'm just going through one of my groups, commenting & Liking (and sometimes 'favoriting') featured images. I do this if the Discussion tab seems to only be "Thanks". One photo has three features displayed underneath, and the artist made several comments thanking group leaders for Features that do not show under the image.

Just trying to understand all the intricacies. Don't all received Features show under the image? If not, why not? And if not, who selects those that do?

Thanks!