Technically, PostgreSQL is a DBMS, not a database. I.e. “PostgreSQL is the worlds’ best DBMS”, but not “best database”. The problem is, if you call the DBMS a database, so what do you call the database (collection of data, tables, etc.)?
When I knew nothing about databases, and was trying to read stuff on the web about those, it was very confusing trying to understand what the author talks about when he uses the term database, is it about a DBMS (software), or it’s about a database (data). So, yeah, it’s a problem, at least for beginners.