Hi there!
Thanks for your query.
Yes, Helix Ultimate is a framework as well as a template too. It helps you to configure your header and footer area, that means outside of the Component area. And SP Page Builder helps you to create, edit, modify your page contents and you can style them as you want with it within your component area. Hence, you need both to make sure your overall site editing is fun with visual frontend drag and drop fashion.
Now if you want to compare the Helix Ultimate with the default Cassiopeia, then Cassiopia doesn't have any template options, so you have to create and style menu by your own. On the other hand you have a variety of settings that can control your Header, footer along with logo, menu, social icons, contacts, User account control... and many more!
You will find them within the elix Ultimate documentation:
https://www.joomshaper.com/documentation/helix-framework/helix-ultimate-2/template-manager-tips
Hope this helps!
Best Regards