Scan configurations can be used to control numerous details of how a scan is performed, such as the maximum link depth of the crawl, or what types of issues to report. If no configuration is specified when setting up a scan, then Burp Scanner will use its default configuration, which is suitable for typical websites.
You can specify multiple configurations for a single scan, and these will be applied sequentially in the same way as when launching scans using Burp Suite Professional. Each configuration can define settings in one or more specific areas. Applying configurations sequentially allows you to specify a general configuration followed by more specific configurations. When these are applied, they will be combined to determine the full configuration that is actually used.
When selecting scan configurations, you can:
Notice that if you hover over the configuration, you can click an icon shaped like an eye to see details about which settings this configuration changes. Collapsed sections contain settings that are unchanged from the standard configuration, whereas expanded sections indicate that this configuration makes changes to settings in this section. For "Crawl strategy - fastest", you can see that the "Crawl optimization" section is expanded because the "Crawl strategy" is set to "Fastest". If you select a custom scan configuration, only the raw JSON content will be shown.