Scroll depth refers to the distance a user scrolls down a web page, typically measured in pixels. It tells you how far a user has scrolled from the top of the page to the point where they currently are. For example, if a user has scrolled 800 pixels down on a web page, their scroll depth at that moment is 800 pixels.
Scroll percentage, on the other hand, represents the proportion of the web page that a user has scrolled through. It is measured as a percentage, indicating how much of the page has been viewed relative to the total height of the page. For example, if a user has scrolled halfway down a web page, their scroll percentage would be 50%.