First, Divi has enhanced just about every module they have to bring every modern feature that you would come to expect, including a newly released theme builder. On top of that, they have released a new template manager and a gazillion templates to go along with it.
Elementor, on the other hand, built an entire “Theme Builder” so you can use Elementor to design headers / footers / archive pages/ post templates, and much more. Also the recently added a powerful popup builder and motion engine.
So in the past 12 months, Divi seems to have its own focus but at the same time is always playing catchup with Elementor. Whatever comes to Elementor, I am sure Divi will eventually build, including the “Theme Builder”.
The decision between Elementor and Divi is going to come down to 2 things, cost & ease of use. Divi costs less but lacks a popup builder (if that matters to you), and I find has a much steeper learning curve. Also the Divi theme builder is not as robust as Elementors, but that is mostly because it's so new.
Elementor has an annual license, a much better workflow, and a more robust Theme Builder.