An earlier question ([see here](https://german.stackexchange.com/questions/7648/menschen-vs-leute)) asked for the difference between *Menschen* and *Leute*. I would like to understand how "Volk" relates to these (like in the Reichstag inscription, see picture below). Is it more professional or something? I mean, it's carved on the Reichstag building, so it's pretty significant... Several dictionaries listed it as more 'folks', but I'm not sure that connotation matches things like this- [![enter image description here](https://i.stack.imgur.com/98M0Q.jpg)](https://i.stack.imgur.com/98M0Q.jpg) It seems like a very formal usage, at odds with a 'rustic folk' connotation. 

How does this compare to the others? They all seem to mean "people," but with different connotations. What are the differences?