Adobe Dynamic Media Classic is the more common of the two in our index: it runs on 160 websites against 147 for Arc XP. Counts come from real scans, not vendor claims.
Adobe Dynamic Media Classic is a platform that enables customers to manage, enhance, publish, and deliver dynamic rich media content and personal experiences to consumers across all channels and devices, including web, print material, email campaigns, desktops, social, and mobile.
Arc XP is a cloud-based digital experience platform that helps enterprise companies, retail brands and media and entertainment organization create and distribute content, drive digital commerce, and deliver powerful experiences.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.