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 Textile is
Textile marks header cells with |_. and data cells with plain pipes.
Redmine, and older Rails applications.
What changes when you convert CSV to Textile
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.
The header row is written with the |_. marker so it renders as a header.
What carries over from CSV to Textile
One property of the CSV has no home in Textile, and it is worth knowing which before you convert.
A line break inside a cell ends the row in Textile, so line breaks are replaced rather than carried through.
Textile 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 Textile 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 Textile file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the Textile.