.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.

.xls The .xls format is the default file format for spreadsheets created in Microsoft Excel, particularly in versions before Excel 007. This binary file format can store data in cells organized in rows and columns, and it supports formulas, charts, graphs, and various formatting features to manipulate and visualize dataThe .xls format was commonly used in business, finance, and any field requiring data analysis and presentation but has since been largely replaced by the more advanced .xlsx format.