.xlsx (Microsoft Excel Open XML Spreadsheet) The .xlsx format is the default file format for spreadsheets created in Microsoft Excel, starting with Excel 007 and later versions. It's part of the Office Open XML specification and uses XML and ZIP compression for smaller file sizesThe .xlsx format supports complex spreadsheets with data, formulas, charts, pivot tables, and various formatting. It is more efficient and secure compared to the older .xls format and is widely used in business, education, and personal data organization.

.csv The .csv (Comma-Separated Values) format is a plain text format used for representing tabular data. Each line in the file corresponds to a row in the table, and columns in a row are separated by commas. This format is widely supported by many applications, including spreadsheet and database software. It's commonly used for exchanging data between different programs and for exporting and importing large amounts of data due to its simplicity and wide compatibility.