Divider and Spacer are two useful widgets in Elementor which help you to create more structured template for your website.
Difference between Divider and Spacer in Elementor
The Divider element allows you to add styled, horizontal line to add a divider between other elements. You can change the line type, its width and color, and other settings.
On the other hand, Spacer element allows you to add spacing between elements in Elementor without adding any visual element.
Which should we use?
It really depends on the situation you want to use them. If you want to add a horizontal line before or after your content, you can use Divider element. But if you just want to have more control on spacing between elements, you should use Spacer.
If you want to learn more about Divider element, please refer to this article.
Also there is a Flex Spacer element which you can use to add space between items in flex column. Read more about it here.