We currently have two separate tags for publications and papers. As far as I can tell, they're identical; both discuss research articles. I propose to merge them, but just in case I'm missing some nuance, I wanted to bring it up here first.
I imagine that publications is broader than paper: a book chapter is a publication, it's not a paper. Probably, so is a popular science contribution (I've never heard those referred as “papers”, more like “pop sci articles”). Now, whether that difference is used in practice, I cannot say.