The default WordPress themes, for example, are essentially “starter themes”. They are more template based, with each template file (index.php, page.php, single.php, etc..) geing filled out with content code and including partial template files to fill in the specifics for that kind of page or page. Whereas a pure framework theme like Freelancer generally builds a single framework structure through action hooks and then hooks into those actions to build out the specifics of the various pages.
With all that said, the simple answer is that frameworks are generally MUCH more flexible to work with, though may be a bit confusing at first glance. But once you go action_hook you never go back! 😀