It is confusing for the public to understand the differences between Bookbinder, Book Restorer and Book Conservator. Book Conservationist is never used, except by the uninitiated. Below are how some of these terms are commonly used — more precisely, how I wish the terms were commonly used — in the United States.
Bookbinder: Someone who makes books consisting of partially prepared materials from other crafts, rebinds and sometimes repairs older books.
Book Restorer: Someone who makes old books look an imagined “new”.
Book Conservator: Someone who preserves the historic, intrinsic, artistic and artifactual value of books through preventive measures and physical intervention.
The New York Public Library has muddied the waters even further, with a program called New York Public Library Conservators. In this case, the term “Conservator” means someone who supports or maintains NYPL financially. This adds confusion, and creates the need for more explanation. But if you have an extra $15,000.00 – $24,999.00, you can call yourself a New York Public Library Carnegie Conservator, which sounds like an endowed professional position.
Further resources if you want to read more of my rants discussing these terms:
https://jeffpeachey.com/2010/03/30/outside-of-the-text-my-work-in-book-conservation/
https://jeffpeachey.com/2010/03/11/a-future-for-book-conservation-at-the-end-of-the-mechanical-age/
http://www.bookbindersmuseum.org/the-future-of-book-restoration/ The second comment.
https://jeffpeachey.com/2013/05/07/book-conservation-and-book-restoration-and-ngrams/
https://jeffpeachey.com/2008/11/11/comments-on-clarkson-conservation-and-craft/
Peachey Conservation 
I was recently featured on a PBS series “A Craftsman’s Legacy” and the title of my episode was “The Bookmaker” – place your bets here ladies and gents…..
Since we once had an HR person (who was evaluating our work for potential reclassification from clerks) tell us we were “book janitors,” I put a sign up in the window of my private practice that says “The Book Doctor is IN.” It gets people in the door, and then we can have a conversation about conservation.
I work in a conservation lab.There are no book conservation courses in Australia (from which I would earn a piece of paper); I’ve been learning at the bench, and going to various courses with book/paper conservators. Could I call myself assistant book conservator or conservator in training? Do you think that a piece of paper gives you the right to the title conservator, or can learning in situ give you as much info and experience?
Well, there are really no rules at this point. Anyone can call themselves a conservator if they want to. I’ve met talented conservators who were largely bench trained without a formal degree as well as talented conservators with Masters degrees. Although I was largely bench trained, I now sometimes teach in degree programs, and am more and more convinced that at this point in time it is the best way to enter into and continue learning the myriad of skills conservators need. There is a prodigious amount of thought that goes into devising training for conservators, and I feel it is quite difficult to do it yourself. And of course, even in a degree program (a piece of paper) much learning takes place by working on your own, interning, workshops, etc. which is not per se the exclusive domain of an MA program.
At least here in the US, if there were two identical applicants skill and experience wise, and one has an MA and the other doesn’t, I suspect the one with the degree would get the job.