WPBakery, Elementor free version, and Visual Composer free version are just page builders. This means that you can design only the content area of your page with them. Porto 6.0 adds templates builder which enables you build header, footer, block, single product, shop, etc as well as page using WPBakery, Elementor and Visual Composer. This helps you build your whole website by only drag and drop elements without any programming skills.
To get to the Templates Builders section, please go to Porto -> Templates Builder. There are block, header, footer, product and shop builders. After you create header, footer, product and shop builders, you need to set display condition where you want to display. You can display blocks using Porto Block element, block display options(Theme Options or Meta box) or shortcode.