He might be referring to more work for an MS Comps, which is the non-thesis Master's. Instead of writing a thesis (which counts as 6 credit hours) you have to take 30 credit hours worth of classes, and half of those classes must be "MS Comps," where at least 50% of your grade in a class (at least here at UMD) must come from exams. I am doing a thesis-based Master's, so I guess you could say I am able to take all my classes just as a PhD student would - in that in most classes there is a research project due at the end of the semester on a topic of your choosing. This allows you to shape the course to your liking and interests.
For me, being a Master's student has afforded me just as many research opportunities as a PhD student; I just won't be here as long.