Difference in pee smell syrian vs dwarf

[peculiarplanets]

I've got Sock (hybrid dwarf) for 4 days now and I've noticed that his pee smells a lot different than Jupiter's (Syrian). I've had dwarfs in the past but that was a couple of years ago so I don't really remember what they smelled like. Sock is a male hamster and Jupiter is a female. I never really smell Jupiter's cage much when sitting in front of it but after only 4 days Sock's cage has a pretty strong smell. Or is it the difference in gender? Just trying to make sure nothing is wrong..