ok , lemme try that 1 more time with some info filled in here
a raw sysex is used if your just working around the studio and you need to get a message to a particular divice. raw sysex is written in hexidecimal.
sysex that is embedded in a midi file would be sent during song playback simmilar to control change info. say at messure 27 you want that GM mode thing to happen. rather than sending a standard CC message and haveing every thing listening on that channel change to GM mode you send a sysex to the 1 piece of gear that you want to have change modes.