There is what we consider a “slight” difference as it comes down to simmering times and what is simmered. Stock is a bit heartier and uses whole parts of meat and takes longer to simmer.  However, that is quite technical, as you can simmer both bones, vegetables, and meat parts together, take the liquid out after two hours, and have broth. Add more liquid and simmer again longer and you have stock. It is only a timing issue. Broth is also typically seasoned while stock is not.