What can you do with synchron32 that you can't do with the step sequencer?

Map each sequence to an individual note on a keyboard. Scroll up and down a "full piano roll view" whereas the stepsequencer only shows an octave and allows you to add lines one at a time.

Also, Im assuming that you are talking about the step sequencer in the piano roll view, instead of the the project5 pattern editor in step mode, in which case the pattern editor in step mode far surpasses both of them in its flexibility.