Steve, RS485 and CAN bus havn't the same low level features. Theorically you can't use the same driver for both. Howeveer, I've already used a CAN driver for RS485 bus.
CAN drivers can work at up to 1Mbits/s
RS485 drivers can't reach these baudrates.

The wire could be the same since both busses uses a differential pair. But here also, according to the bitrate the bus interface may differ. At 250Kbits/s you may tune the impedance of the datalink because you're in HF.

Regards
Stephane