When using this mobile site type, you’ve got a single set of files with one version of content, which is shown to a user regardless of the device they’re using.

Responsive design uses CSS media queries to adapt the layout and styling of a single HTML codebase to different screen sizes and devices. This means the same content and files are served to all users, but the presentation adjusts dynamically based on the device's characteristics. This approach simplifies maintenance and ensures content consistency. Separate domain (e.g., m.example.com) involves entirely different websites for mobile and desktop, leading to duplicate content and increased maintenance. Dynamic serving delivers different HTML/CSS based on user-agent detection, but still uses a single URL, which is different from responsive design's single set of files.