i want to be precise about the state of the work.
a prototype can show an interaction without proving the service behind it. a preview can show a page without meaning it is live for customers. a successful build can show that code compiles without showing that the user journey works.
those distinctions might sound small until someone relies on the wrong one. then they become product behavior. a clear label protects the person looking at the work and helps me know what evidence i still need.
i would rather describe a thing accurately while it is unfinished than make it sound complete before it is.