One thing that’s so fascinating about Prokofiev’s symphonic cycle is how completely different each symphony is from one another. I mean, just look at the difference in style between the first two symphonies! 
It really is quite a thing. The biography I've been reading speaks of #1 being Haydnesque, with a work in which Haydn 'would retain his own mode of writing, but also assimilate a few new things', and by the time he gets to France and starts #2 in 1924 he's writing 'a Symphony of Iron and Steel, stark and shocking and, above all, modern'.
Fascinating stuff! Am enjoying reading the context of his life and composing. Aside from his own growth and personal influences, what a world in transition.