TSV is a Tab Separated Value format. Unlike Comma Separated Value (CSV) it contains ONLY tabular character to distingish columns. CSV my be divided by comma, tab, semi-colon, pipe etc. It also has some rules to separate columns with data inside them, if it contains special characters (a.k.a. escaping). TSV alsways wrap dta into quotes if separator is comma. Like [1..3] becomes '"1","2","3"' (with tabs) and [1..3] becomes '1 2 3' (with comma)
Strict rules also give TSV ability to be little bit faster than CSV
See https://github.com/eBay/tsv-utils/blob/master/docs/comparing-tsv-and-csv.md