It’s the same Debian base under the hood, but has:

• A more user-friendly installer (I know Debian’s has improved with Trixie, but Mint’s is still easier IMO).
• A newbie friendly welcome screen that walks them through setting up a snap shot back-up tool, theming, updates, firewall, as well as easily providing a link to help documents, and shows the user the software center exists.
• The excellent Mint Software Centre Appstore (I don’t think that comes with Cinnamon on a standard Debian install, I think it’s just the terminal).