xlsx The .xlsx is an open source filename extension format developed by Microsoft in collaboration with ISO/IEC and ECMA. It is part of the Open Document family of file formats. The .xlsx is associated with spreadsheet authoring applications particularly with Microsoft's Office Excel 2007 and above. The format has existed since 2005 and is also supported by several other proprietary and open source spreadsheet authoring software other than Microsoft's Office Excel. The xlsx format is the default filename extension for all spreadsheet documents produced using Microsoft Office Excel 2007 SP2 and above.
csv The comma-separated values file format or CSV for short is a common cross platform file format used for information exchange between disparate devices, systems, and software. Mainstream usage of the format begun in 2005, with RFC 4180 forming the basis of its specification. The format's strongest feature is the ability to store relational tabular data in a plain text format which can be imported and/or exported to any compatible application. Because of this feature and the relatively small file size, CSV is commonly used for exporting and importing data from populated databases or spreadsheet files that use a proprietary format, to other systems and applications that utilize different file formats and architectures. The csv format is limited though in its inability to represent records only from a relational data source. It does not support object oriented or hierarchical databases.