How does JSON-LD relate to JSON Schema?

Hello!

I've worked with JSON Schema for a while and am wondering how it relates to
JSON-LD.

Of course JSON-LD is about semantics and having URI's to identify things.
JSON Schema is more about describing a data format in general - similar to
XML-Schema. (JSON Schema could be use to describe JSON-LD).
I think both are good for auto-generating API's, Documentation and making
data more machine readable etc.

But I'm not completely sure how both relate to eachother. Can JSON-LD be
used to substitute JSON Schema? What are your opinions on that?

Regards,
Simon Heimler