meaning of "near identity of one to the other"

I'm reading the chapter 17 of this pdf, explaining the preposition "OF". The sentence is

In (5), the integration of Subject into Landmark amounts to near identity of one to the other:

(5) The State of California

I don't understand the meaning of this sentence, especially the meaning of "near identity". Is "near" the same meaning as "similar" here? Does the sentence mean that the integration of Subject into Landmark makes the identity of Subject and Landmark vague?

The pdf is a book about English so some words are terms used by the author, such as Subject and Landmark, they are explained on page 6. Also to understand the context, please click the link to the pdf and go to Chapter 17. My question is from the second page of chapter 17.

I really appreciate it if anyone can help me understand it.

He means that "California" (what he calls the Landmark) is virtually the same in meaning as "The State of California".

He contrasts that with cases such as "The garden of the house" where the spatial object (garden) is more distinct from the subject (house).