So the Core comes with one algorithm from the ptichfactor.  It comes with 25 presets loaded – these are different saved settings of the algorithm that come from the factory.  So I think one sounds like a chorus effect; I think another one is a crazy photon beam sound.  All of these presets use the one algorithm.  Say the algorithm has ten knobs, the presets have the knobs saved at different positions.  You can turn the knobs to make a new sound then save your own user setting (then you would have 26 presets – 25 from the factory, 1 of your own).  (Oh, and obviously you can make more than one user preset; this was jsut an example.)  I hope that makes sense.     

I love the H9.  I have two of them.  The H910 algorithm is cool.  You will have fun with it and get usable sounds.  But, you will want and will buy more algorithms.  I think Eventide has a program where you can upgrade your core to a MAX over time as you buy more algorithms.  I definitely recommend the MAX.  I bought a Core after owning a MAX.  I did not have to pay the more expensive price for the MAX but was able to upgrade the Core for free to a MAX since I owned a MAX.