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.
XLSMMicrosoft Excel Macro-Enabled Spreadsheet
Files with XLSM extension is a type of Spreasheet files that support Macros. From application point of view, a Macro is set of instructions that are used for automating processes. A macro is used to record the steps that are performed repeatedly and facilitates performing the actions by running the macro again. Macros are programmed with Microsoft's Visual Basic for Applications (VBA) from within the Excel Workbook using the Visual Basic Editor and can be run/debug directly from there.