What is JSON?
The format the web runs on. Nested objects and arrays, real types, and a syntax small enough to fit on a postcard. It maps badly onto a grid, which is why converting deeply nested JSON to a spreadsheet always involves losing something.
What is TSV?
CSV with tabs instead of commas, and the better choice more often than people realise. Tabs almost never appear inside a field, so the quoting rules that make CSV parsing miserable largely evaporate. Anything with prose, addresses or European decimals in it is safer as TSV.