What is DOCX?
What Word has saved since 2007: a zip of XML parts, replacing the binary .doc that came before it. It is a page format through and through - paragraphs, styles, revision marks - with no notion of a typed value anywhere in it, so a table in a Word file is text arranged in a grid rather than data.
What is CSV?
The least glamorous and most durable data format there is: rows of values separated by commas, readable by every spreadsheet and database ever written. All its subtlety is in quoting - a value with a comma in it has to be wrapped in quotes, and a quote inside that has to be doubled.