It (the 315p) is more of an exploration based version so it'll be able to travel further and carry more at the expense of less weaponry. I believe you can upgrade the the 325a to the 315p or vice versa if you change your mind, although it won't be cheap. I'm hoping that I will be able to get away with less weaponry as I'll hopefully joined up with a clan by release. I'm hoping to eventually get hold of a bigger ship( in game using the ingame currency) but as I didn't have the money originally to pick the ship I wanted, I've had to settle for a 315p :/.
it's 5$ more and i can upgrade it in game, okay.
well, tbh i am only really interested in the exploring side of things, dogfights aren't really my thing. but, the dogfighting module will release way before the exploring module, so the 325a makes more sense, till the exploring module release i'll have the in game money to make it fast.