difference

A vacuum frame holds negative and photosensitive material in contact, uses an external light source for exposure.
A platemaker may be a vacuum frame with built-in light source, or it may refer to a lithographic camera-platemaker, a lithographic plate developer, a photopolymer relief exposure-and-washout unit, etc, depending on the speaker.
A platesetter is an imagesetter that works with lithographic plates, bypassing traditional film and stripping.
A plate processor develops exposed plates, either lithographic or photopolymer relief plates, depending on what it is intended for.
When someone talks about a platemaker or plate processor, context is important. You can expose photopolymer relief plates in a vaccum frame or platemaker with an appropriate light source, but it isn’t as efficient as using units made for photopolymer. You can’t washout a relief plate in a litho plate processor. And trechnology isn’t yet to the point where we consumers can make relief plates with platesetters.

thanks

parallel is right on. The only thing I would add is a vacuum frame (and for some platemaker/plateframe) uses a rubber bladder or foam base and typically has a glass top on a hinged frame. When closed and the pump running all the air is removed from between the base and the glass giving you tight contact between your mask and photosensitive material.

If you look into it there are some plates out there you can expose in an ablative platesetter. The unfortunate side is all it’s really doing is using the ablative laser to cut a mask that replaced the tradition negative for photopolymer. You still have to make a second UV exposure of the plate then wash out and and make the last exposure to harden.

There are some flexo/letterpess specific laser engravers out there but their cost is astronomical.

Even small “hobby” CO2 engravers are up around 10K new.

on the other hand you can most likely get a quality vacuum frame and UV light source from a print shop that’s gone CTP for cheap.