Kind of hard to describe the difference. But if i try to make “analog type sounds” the Peak has the edge. Just sounds a bit smoother and better. Its one of those things that is hard to notice in a mix, but when just playing them side by side there is a noticeable difference. So for those type of sounds i prefer the Peak.
The Hydra is better at harder and sharper sounds. With the fm and wavetables it can get a bit more “in your face”. Peak can ofcourse sound hard too if you combine FM with Wavetables, but the Peaks wavetables are based on additive synthesis, and are slightly rounded compared to the Hydra.
The hydra also has much more modulation posibilities. So it have an even wider range than the allready very versatile Peak.
One thing about the Hydra is the variable latency you get when using the Mutators. Alot of people dont notice, or care about this. But i often sample each key when using mutators and correct this on my Akai Force. Not just because of the latency, but also because i then can use the Hydra for more than one sound at the time.