What is the peculiarity of child domains from the usual added domain?

Question

Active Directory

I'm wondering what are the differences between creating child domains from creating and adding a regular domain to an Active directory forest other than the suffix? Why exactly create a child domain?
Users can have access within the scope of the entire forest?
Are there any differences, for example, an access difference or something like that?

Answer 1

Differences in the presence of trust relationships between domains or their absence.
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