I worked as a developer for VISTA and one or two of their clients – back in 90s! So, this is based on what I knew then. As another contributor said, it’s a development language aligned very much to the publishing industry (a package for books, another for journals) – but there was also a ‘financials’ package. At that time, there were non-publisher clients who only took the financial package.
Progress (I think) is an RDBMS only – so, not the same thing.