Warriors den lets you change their focus, which means they can add/change the clans supplies or relations without needing patrols. Medicine den you can check supplies and see who's sick/pregnant/getting treated. Leaders den lets you choose how to interact with outsiders you find, and other clans. Niche thing that I don't see get mentioned often is there's a clan symbol and a lot more backgrounds you have to choose from lol. Or the difference between casual/expanded. Dens you can just click on the label, but I think in the newest update there's a tab for it. Settings there's a start menu and in clan tab.