Text diff is operating on a linear structure, an ordered list of lines (and this successfully for 43 years already ...)

JSON describes a tree structure, and already the question how to order one level before comparing is problematic because the RFCs are not clear.

Likening both is tempting but problematic.

But I agree with you, I don't wanna spend more thought on this neither ...

...and a trivial solution is obvious:

Patch: Remove all elements of A and insert all elements of B.

Problem solved, thread closed! :)