Ilmbase vs. openexr: what are they, what do they do, and what's the difference?

This morning I updated two computers, both running EndeavourOS. I saw an option to replace ilmbase with extra/openexr and, as the default was Y, I selected it and allowed the update to proceed, which it did normally.

My question is in the title of this post: what it ilmbase vs. openexr? Does one have an advantage over the other? And what would have happened had I NOT selected to remove ilmbase and replace it with openexr?

Thanks for any information.


In addition to these three links, when pacman throws you And it is because that way he eliminates that library and looks for a replacement for it. The developers do it that way. if you face pacman putting N instead of Y the update is not carried out, most of the time.
The rest is explained by the links, to read.