Difference between id and uuid

The story id is the old default id of the story, we could call it also a legacy. We keep the id in the JSON to not introduce any breaking changes into our API, as a lot of older projects may use its value. We strongly recommend you use uuid in your future project. The uuid is also already used on the objects of the links API .

What are the _uid in the content itself?

The _uid in the content are the ids of each component in a Story that enables us to make deep links in the editor and allows us to open them based on clicks. They are only unique inside one entry but not across entries. You can not query by them or make references.

References can only be made on the uuid on the Story object level which is the ID of the Story (Entry) and is unique throught Storyblok.