The original data are encrypted and re-encrypted multiple times, then sent through successive Tor relays, each one of which decrypts a "layer" of encryption before passing the data on to the next relay and, ultimately, its destination.
The original data are encrypted and re-encrypted multiple times, and then sent through a virtual circuit comprising successive, randomly selected Tor relays. Each relay decrypts a "layer" of encryption before passing the data on to the next relay and, ultimately, its destination.