All the other

[Xinfu]

What's the difference?:

-This is the only true version of the story. All other versions are frauds.
-This is the only true version of the story. All the other versions are frauds.

Is the second one more definite than the first one, with almost no difference in meaning?

[Rusty]

Both can mean the exact same thing.

However, by using the article, we are led to believe that the speaker has read the other versions and has singled out the only true version.
Without the article, the speaker asks us to take his word and believe that no version in existence, or yet to be written, contains the truth.

[wrholt]

What's the difference?:

-This is the only true version of the story. All other versions are frauds.
-This is the only true version of the story. All the other versions are frauds.

Is the second one more definite than the first one, with almost no difference in meaning?

Yes; for me there is a small difference in meaning. Some people may not distinguish that difference.

Saying "all other versions" suggests that you are making a statement that is universally true, even for other versions of the story that you may not know about yet.

On the other hand, saying "all the other versions" suggests that you are making a statement about a defined set of stories that you have examined, but not about any other stories.

[Xinfu]

Thank you~

Are the differences you suggested applicable to this?

-All (the) three of us did not know the answer, so we failed the test.

[Rusty]

No.

The determiner 'the' is not used when 'all three' appears.