Research with M.S. degree?

Hello, everyone!

So, I have been looking at some interesting labs at prospective grad schools and I have seen that some professors from these labs go by the title "Research Speech-Language Pathologist" and only have a master's degree. I know that one needs a doctorate to have the most autonomy in research, but is there a position for SLPs with a master's that is more than a research assistant (which you could have with only a bachelor's degree)? If so, does one need a M.S. over a M.A. degree?

If you or anyone you know has pursued this, could you tell me more? I am interested in being a practicing clinician and researcher, though I thought I'd pursue research later because I am not sure that I am ready to commit to a doctorate program.

Thanks for your help!
This is curious to me. I have not heard of this and I did not see this at my graduate school, but my university was a PhD-granting institution and some are not so maybe that is the distinction. The only thing I can think of is perhaps those professors were actually PhD students working towards the doctorate...many teach alongside their own coursework and research while they're going through the doctoral program. I could be wrong.
Thanks for your response! Actually, I have seen one whom I know is a professor and she works at a PhD-granting institution, so I'm perplexed :/