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 PDF is
PDF describes a page: glyphs at coordinates, not rows and columns. A table in a PDF is a visual arrangement, not a data structure.
Reports, invoices, statements and anything sent to be read rather than processed.
What changes when you convert CSV to PDF
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 table is drawn into a paginated document with the header repeated on every page, so a long table stays readable past page one. Page size, orientation and font size are all adjustable.
The table is laid out for paper, which means it now has a page count. A wide table on portrait A4 will be cramped; switch to landscape and drop the font size a point or two and most tables of ten columns fit.
The header row repeats at the top of every page. Without that, page four of a long table is a wall of numbers with nothing to say what they are.
Long values wrap inside their cell rather than being cut off, so the row grows taller instead of losing text.
What carries over from CSV to PDF
CSV records 3 things about a table that PDF has no way to hold.
Nothing in PDF records that the first row is a header. It is drawn at the top and looks like one, which is all that is left of the distinction.
CSV can be read one record at a time. PDF 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.
PDF is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the CSV if you will need the values again.