I know what you mean as I had the same experience where the modules in my undergrad (biomed) were the same, on paper, as the modules in my master's. Some master's are quite general (like the one I did, covering a breadth of biomed topics) others are more specific/vocational. However the way you are taught is different. For example, I did a cell biology module at undergraduate and a cell biology module in my master's. However at master's I didn't get given "lectures" for most of my modules, instead we either would have to go and research a topic and then have discussions about it in class consulting primary literature. Or we would be given several papers to read relevant to the module and we would discuss them in class in depth. Therefore if we were covering something like atherosclerosis we weren't learning about the multiple pathophysiological mechanisms like we would have at undergraduate, we were learning about a specific mechanism and discussing how that mechanism has been researched, the evidence for that mechanism, and kind of placing it in context with the wider knowledge of atherosclerosis.
I find that I have not really learnt anything new in my master's in terms of knowing more about biomedicine as I think by third year undergraduate you can read primary papers and understand what is happening. However, my perspective on the topics has shifted and I am a lot more critical and able to synthesise the results of a variety of papers to get insight into different concepts and to place them in context with other theories, etc. I also think my skills have improved, my scientific writing is a lot better and I am much more comfortable doing presentations and speaking up in seminars.