I guess I'm lucky, my 2 girls look slightly different, they're from the same breeder but about 2 months apart, I don't know how they're related if at all. Anyway Lulu, the eldest, has a thinner stripe on her head, that's the physical, the personality is she is more aggressive (she crabs, lunges, and does bite). Skadoosh on the top of her head her stripe gets a wide spot, physically that's the best way to tell, just looking at their faces it's harder to tell apart, her personality, well she's the sweetie pie. They both will hide at times, Skadoosh, although shy, she wants to come out and run around more than Lulu will, they don't stay on us for long periods, they like to explore. Oh, and another way to tell them apart for sure, stick your hand near the cage or Lulu, she'll let you know it's her.
Now that I've explained how to tell mine apart, I have to ask, is there any markings that vary even slightly, by shape or shade? It's hard for me to tell by photos, but sometimes just the slightest variation can help and yes that goes for both physical and personality for sure. Like said already, in time you should be able to distinguish between the 2 a little better.