Não, eles são absolutamente os mesmos. A seguir, uma citação do Kernel do Linux em poucas palavras, de Greg Kroah-Hartman
debug
Enable kernel debugging.
Cause the kernel log level to be set to the debug level, so that all debug messages will be printed to the console at boot time.
quiet
Disable all log messages.
Set the default kernel log level to KERN_WARNING (4), which suppresses all messages during boot except extremely serious ones. (Log levels are defined under the loglevel parameter.)