The document compares the AdWords UI and API, describing how they map to each other. The UI uses clicks and text inputs for human interaction, while the API uses method calls and messages. The basics like campaigns and ads are represented by tabs in the UI but have dedicated services in the API. Reporting in the UI integrates with management, allowing customization, filtering and downloads. The API accesses reporting via the ReportDownloader using report definitions, selectors and AWQL queries.