I think, the .tar file has the cluster management suite files included and its an archived file. It has both the CMS and the Switch IOS file, compressed into the .tar file (an archive format used commonly in Unix systems).
You will need to use the archive tar command to untar (uncompress) the IOS and CMS files into the switch.
The .bin file is just the compiled IOS file. You can use the regular tftp file to load the software on to the switch.
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus