...
The data behind the two versions is identical.
Resources
The documentation of the API version 1 can be found https://labs.deutsche-digitale-bibliothek.de/app/ddbapi/
...
In order to use version 1 you might need an API key. As developing new applications using version 1 is dicouraged, new API keys are not issued. Using version 2 all endpoints are usable without an API key.
...
The endpoints under /items are about the same as in version 1. There are very minor changes to the AIP model used, mainly due to the fact then that other XML libraries are used internally. All items endpoints except for the the /source/record resources now support XML as well as JSON responses.
A new endpoint provides a citation file in bib format for newspaper items.
...
Version 2 of the public DDB API offers the possibility to save favourite objects aka. bookmarks for logged in uses users and allows organizing these bookmarks in folders. Details on the endpoints to manage Bookmarls Bookmarks can be found here: Favourite API
Furthermore, starting from Backend 7.3 it is also possible to save search queries for logged in users, details on this can be founf at Saved Searches API
...