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 reStructuredText is
reStructuredText simple tables underline the header with equals signs and align columns with spaces.
Python documentation, Sphinx projects and anything on Read the Docs.
What changes when you convert TSV to reStructuredText
The tab is unambiguous, so there is no delimiter to guess. This is the most reliable of the delimited formats to read.
The equals-sign rule under the header is what tells Sphinx the first row is a header. Without it the table renders as data with no heading.
What carries over from TSV to reStructuredText
One property of the TSV has no home in reStructuredText, and it is worth knowing which before you convert.
reStructuredText marks its header cells differently from its data cells, so the first row is written with that marker.
TSV can be read one record at a time. reStructuredText has to be complete before it means anything, so the whole table is held in memory while it is written and a file that gets cut off part way through is not partly usable - it is unusable.
The identifier 007 comes out of the reStructuredText 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 reStructuredText file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the reStructuredText.