What is the difference between "Document Layout Analysis" / "Document Understanding" / "Document Structure Analysis"

All three terms sound super similar:

[…] document layout analysis is the process of identifying and categorizing the regions of interest in the scanned image of a text document. A reading system requires the segmentation of text zones from non-textual ones and the arrangement in their correct reading order. Detection and labeling of the different zones (or blocks) as text body, illustrations, math symbols, and tables embedded in a document is called geometric layout analysis.[2] But text zones play different logical roles inside the document (titles, captions, footnotes, etc.) and this kind of semantic labeling is the scope of the logical layout analysis.

Document layout analysis is the union of geometric and logical labeling.

Source: Wikipedia

The process of document structure and layout analysis tries to decompose
a given document image into its component regions and understand their functional
roles and relationships. The processing is carried out in multiple steps, such as preprocessing, page decomposition, structure understanding, etc

Source: Document Structure and Layout Analysis by Anoop M. Namboodiri

From this I would say that wikipedia calls it "geometric layout analysis" what Namboodiri calls "layout analysis". Wikipedia calls "logical layout analysis" what Namboodiri calls "document structure analysis".
Namboodiri uses "document understanding" as a broader term.

Do I understand this right?

(Is Document Understanding a sub-field of Information Extraction?)