Featured photos are different from a featured photo in that:
- Featured photos are on a profile. A featured photo is on an article/post.
- Featured photos are typically plural (more than one). A featured photo is singular.
none so far.
Facebook seems to have added support for "Featured Photos" on 2016-03-29.
If you go to your own profile URL, you will see a prompt in the left column to "Add Featured Photos" (blue link), below it with a caption "Feature up to 5 photos you love":
After a while, the large preview prompt box disappears and is replaced by a simple blue text link prompt: