What CSV is
CSV is a text file where each line is a row and commas separate the fields. There is no type system, no formatting and no second sheet. Every value is text until something downstream decides otherwise.
Almost every database, analytics tool and spreadsheet can read and write it, which is why exports default to it.
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 changes when you convert CSV to HTML
Reading CSV means deciding three things the file does not state: which character separates fields, how quotes work, and what encoding the bytes are in. Tablizer sniffs the delimiter from the first few lines, handles quoted fields containing commas and newlines, and reads the file as UTF-8.
Semantic markup: a real thead, a real tbody, th for the header row. Angle brackets and ampersands in your data are escaped, so a value like <script> is written safely and shows as text on the page.
What carries over from CSV to HTML
One property of the CSV has no home in HTML, and it is worth knowing which before you convert.
HTML marks its header cells differently from its data cells, so the first row is written with that marker.
CSV can be read one record at a time. HTML 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 HTML 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 HTML file goes wrong.
The quotes around Jonah "Jo" Pryce are written as the HTML entity " in the HTML.