There is no ODK 1 and ODK 2. There is the ODK suite of tools and ODK-X (formerly ODK 2.0 or ODK 2) suite of tools. In each suite, there are tools whose names start with ODK or ODK-X. Each of those tools is versioned semantically (e.g., ODK Collect v1.22.4).
@yanokwa Thank you too much for your answer, it now more clear to me.
I already know the components of each suite (ODK and ODK-X).
I think that the change of ODK-2.0 to ODK-X is very recent, because I read the official book on January of this year (2019) and it still was ODK-2.0.
Now, my next task will be to know the latest versions of components of each suite.
(Sorry for my English, I'm French-speaker)
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