eldritch magic is reality bending, the wierder the more likely it is to work. things moving that shouldnt? two things where you thought there was one? impossible geometries? Eldritch.
beast magic is BIG. big explosions, big destruction, just being big, but also big smothering love and that kind of thing. if its big, its beast.
and then critter magic is probably transformative, possibly informational? not entirely sure about what fits well...