XLSBMicrosoft Excel Binary Spreadsheet File
XLSB file format specifies the Excel Binary File Format, which is a collection of records and structures that specify Excel workbook content. The content can include unstructured or semi-structured tables of numbers, text, or both numbers and text, formulas, external data connections, charts and images. Unlike XLSX (which is based on Open XML file format), the XLSB represents binary Excel workbook file.
Portable Document Format (PDF) is a type of document created by Adobe back in 1990s. The purpose of this file format was to introduce a standard for representation of documents and other reference material in a format that is independent of application software, hardware as well as Operating System. PDF files can be opened in Adobe Acrobat Reader/Writer as well in most modern browsers like Chrome, Safari, Firefox via extensions/plug-ins.