Files with IFC extension refer to Industry Foundation Classes (IFC) file format that establishes international standards to import and export building objects and their properties. This file format provides interoperability between different software applications. Specifications for this file format are developed and maintained by buildingSMART International as its Data Standard.
The XLTM file extension represents files that are generated by Microsoft Excel as Macro-enabled template files. XLTM files are similar to XLTX in structure other than that the later doesn't support creating template files with macros. Such template files are used to generate and set the layout, formatting, and other settings along with the macros to facilitate creating similar XLSX files then.
You can also convert IFC into many other file formats. Please see the complete list below.