What is JSON?
JSON is the shape data arrives in when it comes from an API. Tabular data usually lands as an array of objects, one per row, with the column names repeated as keys in every single one - verbose to read, but unambiguous.
What is TSV?
TSV is CSV with tabs, and the swap removes CSV's worst habit: prose is full of commas and almost never contains a tab, so fields rarely need quoting at all. It is what you want when the data is text-heavy and the quoting keeps going wrong.