I am not sure how to word my question, so please bear with me.
When Backdrop was forked did you ask or take a structure with you? Maybe I should word it like 'architecture / flow logic'
I am not talking about code unless it is at a high level.
And am not talking about goals, values etc, although those would affect the structure.
At some point looking for best practices. :)
I'm not sure how to really help but try the official backdrop page "Why fork Drupal"
Also, Drupal is an open-source project which allows anyone to make a fork of Drupal. For more information about the licensing aspects, look at the LICENSE.txt within the relevant distribution.
I hope this helps.
@able - I understand you were having difficulty with the wording of your question, but l will try to answer.
At it's foundation, Backdrop CMS carries many of the core concepts of Drupal. It uses content types, fields, views, taxonomies, and other concepts in the same way that Drupal does. In many parts of the Backdrop interface, you will not recognize the difference between Backdrop and Drupal.
The biggest change in Backdrop from Drupal is the built in layout system which is similar to Panels (for Drupal), but we think it's easier to use. However, it is the hardest concept to adjust to if you are coming from Drupal. But once you do, I think you will appreciate the advantages.
Backdrop CMS is also different from Drupal 7 in that we have been making small improvements for the last 7 years. Many of the improvements added to Drupal 8 are also available in Backdrop.
You can very quickly spin up a temporary demo site to look around Backdrop here: https://backdropcms.org/demo
Here are some other resources that MIGHT be helpful.
I can confirm, as a regular user, but with a long experience of both Drupal 7 and Backdrop CMS, that what Stpaultim has written is completely true and, in my opinion, a sufficient explanation for your question.
To work with Backdrop CMS you really need to understand the concept of Layouts, which is not an impossible task, you do not need any special programming knowledge, you just need time, exercises, experience and mistakes to learn from.
I would just add a link to another help page:
Good luck with Backdrop CMS, be persistent and you will gradually find that this is a wonderful system with amazing features and yet easy and affordable to work with and administer.