Looks like there is a misunderstanding with the wording. The shape curve stays static.
The shaper mode will cycle over the entire curve.
The loop mode only over a portion of the curve and only while the note is held. Attack and release can be different. See the green area below.
That way you can have a sound ring out once you release the key, for example.
We hype the shaper mode especially, because we have put a lot of work in a new curve tool set. Without it, the shaper mode would only be half as fun. Also it is called shaper mode, as there are a lot of effect plugins out there with similar behaviour, called shapers.
Hope this answers your questions.