Files with CMX extension are Corel Exchange image file format (also known as Corel Metafile Exchange) that is used as presentation by CorelSuite applications. It contains image data as vector graphics as well as metadata that describes the image. CMX files can be opened by CorelDraw, Corel Presentations, Paint Shop Pro and some versions of Adobe Illustrator. CMX files can be converted to other formats such as JPG and EPS.
XLSX is well-known format for Microsoft Excel documents that was introduced by Microsoft with the release of Microsoft Office 2007. Based on structure organized according to the Open Packaging Conventions as outlined in Part 2 of the OOXML standard ECMA-376, the new format is a zip package that contains a number of XML files. The underlying structure and files can be examined by simply unzipping the .xlsx file.
You can also convert CMX into many other file formats. Please see the complete list below.