[heavenlyblue]

How are they different?

In XML you would need to insert tags defining the whitespace so that it would be seen by programs operating on the AST.

Are your “two different structures” any different from the same representation in XML?

[breck]

This is a good point. When building a raw xml parser, these would be 2 different things.

I think it’s a fair analogy to say tree Notation is just a much simpler XML.

At least 2x as simple:

<proof></proof>

proof