Use the Responsive code feature when you want to share the code for responsive serving with your web developer. You copy the responsive (RESS) code to the clipboard so you can share it with the web developer.
This feature makes sense to use if your web site is on a third-party WCM, not on AEM. If it is on AEM, you can deliver optimized images directly through AEM.
HTTP/2 is the new, updated web protocol that improves the way browsers and servers communicate. It provides faster transfer of information and reduces the amount of processing power that is needed. Delivery of Dynamic Media assets can now be over HTTP/2 which provides better response and load times.
See HTTP2 Delivery of Content for complete details on getting started using HTTP/2 with your Dynamic Media account.