XLS is the most popular and common format for creating and editing spreadsheets. It takes its name from Microsoft Excel Spreadsheet, is created using the Microsoft Excel system utility. Document data is stored in certain table cells that have their own address. In cells of XLS files, not only fixed data can be located, but also formulas that allow you to relate the content of information in different cells. Like text formats, XLS makes it possible to format the contents of cells - font, font style, color, text alignment. Files of this format can also be launched using Google Drive.
PDF is short for Portable Document Format, which can be translated from English as “Portable Document Format”. It was developed by Adobe Systems for use by US federal authorities as a tool for storing working documents. This is a universal cross-platform format, which is now standard for electronic documents. It serves to convert text files (including photographs or other images) into electronic documents without any loss. To read PDF files you need special programs - Adobe (Acrobat) Reader, PDF-Viewer and others.