in which situation such a prepositions "until" and"by" could be interchangeable?

This question comprehensively has been edited:Could you think of where or in which situation or condition--or which verbs-- such prepositions could mean the same thing or even interchangeable?

until

by

The documents need to be ready by next Friday.

Here "until" would have the same meaning.

UPDATED: So, you could see both the prepositions has been used with the same verb-- although the meaning of the sentence has been changed. My specific question is about the stative or dynamic verbs, since the preposition "by" could go just along together dynamic verb, and conversely the preposition"until" merely can go with "static" verbs.

Imagine that it takes some time to extend negotiations. Perhaps everybody needs to fill in many forms. There's a lot of administration to do, if you want to extend negotiations. Now look at this sentence:

They decided to extend the negotiations by July 1, 2015. This sentence means that they decided to finish all the administration for the extension before July 1, 2015.

Now look at this sentence:

They decided to extend the negotiations until July 1, 2015. This means that the minimum duration of the negotiations is from now to July 1, 2015. The negotiations will not finish till July 1, 2015.

Thanks in advance