I had a case open with support forever and a day regarding SharePoint Publisher. As the same thing can be done using Active Homepage, I was told there would be no further fixes for SharePoint Publisher
As Bernie mentioned, I think SharePoint publisher was a web-part that would display BAQs.
SharePoint Attachments will let you store uploaded attachments into SharePoint along with some Meta Data. All documents for a company goes into one Document Library and they all share the same folder structure (as does DocStar). As for the two, I can only imagine that one is on-prem and the other is O365. We currently are using O365 attachments.