An XLS file is a spreadsheet that was created using the common system utility Microsoft Excel, which is a powerful tool for creating and editing spreadsheets. This file extension was one of the most popular formats for storing tables. The .xlsx file is the current format for the vast majority of Excel files and has been used since Microsoft Office 2007. Older versions of Excel cannot open new sample files. If you are using MS Excel in a version earlier than Office 2007, the developers offer you a compatibility pack that will allow you to open workbooks with the xlsx extension and save similar documents.
The Portable Document Format (PDF) is a versatile file format that preserves the fonts, images, and layout of the original document, regardless of which of many platforms and which of many applications the document was created on. It was initiated by Adobe and was originally intended for electronic presentation of printed materials. PDFs look the same no matter what device they are viewed on. Whether you're using Windows 10, Mac, Chrome OS, Android, Windows Phone, iPad, or Windows XP - on any software or hardware, PDFs remain the same.