You can't go swimming with the Watch Sport, but it does have
IP68 weather sealing, so it's fine to get wet or wear in the shower.
The key difference between the two options is their target audience (despite both being
IP68 weather -
sealed): the Sport comes with a sporty strap to resist sweat and hardship, while the Classic goes for that more sophisticated look, complete with leather strap (black and grey options are available, the third orange option is reserved for the Sport alone).