Project documentation. The difference between TK and Speck. Western standards?

Question

Specifications

Good afternoon,
Question: Project documentation (I'm talking about custom software development, Russia, on the contractor's side)
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Concept
Specification
Terms of Reference
Work plan
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1) What is the difference between TOR and Specification? Only by the fact that terms are prescribed in the TOR?
2) Who writes the specification? Business Anal? If it is not there, then PM? The developer definitely does not write it?
3) Who writes TK? Business Anal? If it is not there, then PM? The developer definitely does not write it?
4) in what dock it is necessary to register the test plan? Or a separate dock? what? who will write it?
5) what are the criteria for the completion of the TOR / Specification / Concept
6) How does the concept differ from the specification? Only by the fact that it is top-level?
7) in the west there is no TK for sure, but there is a Scope Statement. Does it replace all at once TK / Specifications / Concepts? Or one thing in particular?
8) What other project docks do you use in project management? You can just write without details, I'll google the details later ... although I'll be glad for the details, of course ...
9) What should I sign with the customer? With your boss?
I'm supposed to be the artist's PM
Thank you