What HTML is
An HTML table is a table element containing thead and tbody, with th cells for headers and td cells for data.
Web pages, email templates and anything pasted into a CMS.
What AsciiDoc is
AsciiDoc tables are delimited by |=== and take a cols attribute describing the columns.
Antora documentation sites, and technical writing teams that outgrew Markdown.
What changes when you convert HTML to AsciiDoc
The first table in the markup is used. Cell contents are stripped of inline tags and entities are decoded, so <td><b>Total</b> </td> arrives as Total. Nested tables inside a cell are not descended into.
The header option is set so the first row renders as a header row rather than data.
What carries over from HTML to AsciiDoc
AsciiDoc can express everything HTML holds about a table, so this conversion is about shape rather than loss.
HTML and AsciiDoc can express the same things about a table, so nothing is lost here - only rewritten. The only common table format with real header cells, spans and nested tables. Cells are introduced by a pipe and may carry their own formatting or another table.
That makes this a change of notation rather than of content: the same values, the same columns, the same order, written with the markers AsciiDoc expects instead of the ones HTML uses.
The identifier 007 comes out of the AsciiDoc as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a AsciiDoc file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the AsciiDoc.