rm -rf *.* corrupt your filesystem while
rm -rf / will not do this?
There's nothing special to it,
rm -rf *.* is a command with a filename wildcard, it will recursively remove all files in the current directory that contain a dot in their names.
rm -rf / would give an error about trying to run
rm on the root directory. This is mandated by POSIX:
If [...] an operand resolves to the root directory, rm shall write a diagnostic message to standard error and do nothing more with such operands.
Depending on the shell and its settings,
*.* might also match
.. for the parent directory, but as well as the
/, trying to remove that is also an error.
Neither of those will corrupt the filesystem,
rm will only (try to) remove files using the usual file system calls. The effect on the system at large, or the user's files, may of course be substantial if the first command is executed in a directory containing important files.