UX vs Product Design, what’s the difference?

I've notice that more and more people who used to call themselves UX Designers are now calling themselves Product Designers. I have a rough feel for the differences but I'm struggling to find any good articles on this and I'm wondering if somebody could help to clearly define the two roles in a way that clearly illustrates the differences.

Side thoughts: I guess it's further fragmentation or perhaps an evolution and I suppose it's not completely without value. Traditionally a Product Designer made real world objects but nowadays it is coming to mean digital products as well. That makes a lot of sense to me as they are products, it just further adds to the confusion of digital design roles to outsiders though. If I tell my friends I'm a product designer, ux designer, interaction designer, ui designer (and so on) they have no idea what I'm talking about.

p.s. I know similar questions have been asked but they are more about whether the differences matter. I say they do matter but there's a lack of clarity and definition..