Hi Robbie and Krysta,
You can make two different menucards and asign different categories to them. This way you can choose what you want to display on different menucards. If you want to add the category dropdowns to the navigation menu, simply go to “Appearance -> Menus” and drag and drop the categories under the menu. If a category is included in a menucard page, any link to that category will automaticly go to the relevant page on the menucard 🙂
Hope this helps!