How do dynamic content rules work in Content Builder — rule-based vs AMPscript-based?

Rule-based dynamic content uses the Content Builder UI to define conditions (profile attributes or sendable DE field values) and map each condition to a specific content block variant. Rules are evaluated top-to-bottom; the first matching rule's content is rendered. A default block is shown when no rule matches. This approach requires no code and is ideal for marketers.
AMPscript-based dynamic content uses IF/ELSEIF/ELSE logic inside an HTML content block to conditionally render different HTML sections, call different ContentBlockByKey(), or output different personalisation tokens. This is more flexible and can reference multiple DE lookups, complex computed conditions, and nested logic. Use AMPscript when rule-based conditions are insufficient or when the number of variants is large.