In structure, both widgets are very similar, but there are two main differences.
First, in toggle by default on page load, all toggle items are collapsed but for accordion, the first item is expended. However, The Plus Addons for Elementor Accordion comes with functionally to close all accordion by default or open specific accordion item. Lear more here.
Second, in toggle, you can expand all items by clicking on them one by one, but in accordion, only one item can be expanded at a time and once you click on the previous item will be collapsed automatically.
But if you want to expand all accordion items at once The Plus Addons for Elementor’s Accordion widget gives you that option to expand all or collapse all items on button click. Learn more here.
