Hi there,
the Block Element is great if you have some static content that you want to be displayed in the same place across different places of your site.
The Header Element does the same thing, except it is limited to one position ( without code ) which is below the Site Header. Its advantages is it has dynamic content, so you can create a single header element for all of your posts for example, and it will display the individual posts featuered image, title, meta etc.
We’ll be updating GB and the Block Element in the future to also support Dynamic Content.
So the overall advantage of Elements is you can create and edit content in one place and have it displayed in many places.
For today, what you’re doing is perfectly fine 🙂