its somewhat hard to explain, the oscillators work in a circle, i.e. one modulates, two, two modulates three, three modulates four, and four modulates one again.
That is somewhat like ring modulated FM synthesis. Its a broad spectrum one can attain with it.
There is also a shape knob where you can morph through the different wave shapes, with LFO and ADSR.
They have really a lot in common. I think never the less the Peak is a very good choice, Novation also tends to have a good support, and with the circuit really delivered.