As mentioned earlier despite the earlier Email name, there are also a few templates used for SMS notifications. The SMS templates are much shorter due to the restrictions usually due to the limitations imposed by the SMS providers. A message size of 160 characters is common for a lot of the SMS message providers. A component parameter permits a size limit to be specified (default 160), beyond which the message is truncated.
An SMS message is built up by prefixing the message subject in front of the message body, so there is nothing to be gained by specifying the same 'tag' in both. The reasoning is that unlike with an email message there is no specific 'subject' for a SMS message, so it becomes part of the message itself.
The short nature of SMS messages and the devices upon which they are displayed means that it is probably not worth while spending too much time modifying the SMS templates since they are very likely to be truncated anyway, most probably by the SMS sender.