No, there is one VAST difference between an SMF and a Chord Sequence. OK, two!
The SMF is set in stone. Other than using Markers to reorganize the structure on the fly (and truth be told, few even use this great feature), it comes out the machine identically every single time. Might as well be an MP3, right?
A chord sequence, however, is as fluid and changeable as playing in arranger mode is. You still get to choose when the fills happen. You get to choose when the Variations build and ebb. You even get to choose whether to change styles on the fly, either to a related style or something wildly different. You can put in stops and break/fills where you want, and end the piece whenever you feel like it.
And unlike the SMF, you can take over from the CS and play something utterly different. And then restart it and go back to the chord sequence. All seamlessly.
You can't do any of that with an SMF. Yes, the CS's easiest option is to lay down a quick 4 bar vamp, either on different chords or chords from the chorus, and then solo away on it. But it can be so much more!
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An arranger is just a tool. What matters is what you build with it..!