Music Creator is like a 'light' version of Sonar.
There are less options, but everything is there to get you started (and beyond...)
It's in an all other league as CPA9!! You can still play and edit midi-files, but you can also record audio (like a modern tape recorder) completely digital. You can put in reverb and other effects, even use software synthesizers (which are also included with Music Maker), and then edit, mix and master your music.
Music Maker is, in fact, a complete recording studio inside your computer.
(You can load the free Cakewalk SFZ+ synthesizer in Music Maker, which plays Soundfont files
http://www.cakewalk.com/products/SFZ/default.aspx )