I do not yet have exact details on the differences but I do know that the manufacturer has to "jump through hoops" to satisfy (prove to) the state of California that all emissions regulations are fully satisfied. There is a proviso that the catalytic converter and oxygen sensor have to be able to maintain the standard for a given minimum number of years and miles. This test takes a lot of lab work to prove out which is very time consuming and expensive. In a separate section of the regulations, there is also a requirement for fire safety compliance for off road motorcycles. This is nothing new, but each new machine has to go through all the compliance testing to prove to the government that the machine meets the requirements.