What TSV is
TSV is CSV with tabs instead of commas. Because tabs almost never appear inside a value, quoting is rarely needed and the files are easier to read by eye.
Bioinformatics, log processing, and anyone who has copied a block of cells out of a spreadsheet: the clipboard format is TSV.
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 TSV to AsciiDoc
The tab is unambiguous, so there is no delimiter to guess. This is the most reliable of the delimited formats to read.
The header option is set so the first row renders as a header row rather than data.
What carries over from TSV to AsciiDoc
AsciiDoc can express everything TSV holds about a table, so this conversion is about shape rather than loss.
AsciiDoc marks its header cells differently from its data cells, so the first row is written with that marker.
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.