The main difference, besides age, is that the C330 and C330f take one type of interchangeable viewing screen, while the newer C330s takes another type.
Here is a link to the appropriate section on Graham Paterson's excellent reference:
I've been using an "F" for more than twenty years and given the choice I would rather have that model than the "S" (1) Because the screens are more easily available on the used market (2) Less plastic in the construction (3) The back of the "S" is difficult to open if you need to change film quickly.
I've been using an "F" for more than twenty years and given the choice I would rather have that model than the "S" (1) Because the screens are more easily available on the used market (2) Less plastic in the construction (3) The back of the "S" is difficult to open if you need to change film quickly.