Posted in a comment above, but the idea is that text content is text content, because XML was intended as a document interchange format, not a data interchange format.
When you look at SVG content for instance, you'll notice colors and coordinates are contained within attributes, because it means a document reader which cannot understand some crazy new drawing element would still interpret that data is text content, leaving the document accessible (if perhaps badly formatted).
If you care about that rule, then structured, semantic, non-user-accessible data uses elements for structure and attributes for data. This also lets you ignore the difference between semantic and non-semantic whitespace - no whitespace has semantics.
CDATA sections are (usually) represented in tooling, but should be considered just a text node with different escaping rules (unless your document format actually assigns a purpose, which is a really bad idea from an interoperability perspective). CDATA is not meant to provide a way to embed binary data (both XML and JSON are somewhat bad for information which is not primarily text).
Similarly, processing instructions are somewhat orthogonal to the document format. I believe XSLT is the only spec which defined a standard behavior for them, but there were examples such as commercial document editors which saved information like the cursor position as processing instructions.
FWIW (as a human interacting with JSON) - there are extensions to JSON such as JSON5 which aim to add the extra flexibility that makes data entry easier. JSON5 adds comments, trailing commas, unquoted symbols, single quoted strings, and so on. Perhaps its biggest issue is that it allows non-finite number values like NaN, which makes it a superset of JSON at the data model layer. So you can't be guaranteed JSON5 text can be stripped and quoted into valid JSON text.
When you look at SVG content for instance, you'll notice colors and coordinates are contained within attributes, because it means a document reader which cannot understand some crazy new drawing element would still interpret that data is text content, leaving the document accessible (if perhaps badly formatted).
If you care about that rule, then structured, semantic, non-user-accessible data uses elements for structure and attributes for data. This also lets you ignore the difference between semantic and non-semantic whitespace - no whitespace has semantics.
CDATA sections are (usually) represented in tooling, but should be considered just a text node with different escaping rules (unless your document format actually assigns a purpose, which is a really bad idea from an interoperability perspective). CDATA is not meant to provide a way to embed binary data (both XML and JSON are somewhat bad for information which is not primarily text).
Similarly, processing instructions are somewhat orthogonal to the document format. I believe XSLT is the only spec which defined a standard behavior for them, but there were examples such as commercial document editors which saved information like the cursor position as processing instructions.
FWIW (as a human interacting with JSON) - there are extensions to JSON such as JSON5 which aim to add the extra flexibility that makes data entry easier. JSON5 adds comments, trailing commas, unquoted symbols, single quoted strings, and so on. Perhaps its biggest issue is that it allows non-finite number values like NaN, which makes it a superset of JSON at the data model layer. So you can't be guaranteed JSON5 text can be stripped and quoted into valid JSON text.