I can't help but compare California HSR with Brightline in Florida. There are indeed major differences between the two - Brightline is not high-speed, for one (top speed is 79 mph). And California's route will be 4 times the length (~210 miles long vs ~800 miles). And California has much more track being run elevated (Brightline has had several automobile fatalities from drivers going around the crossing gates)

But .. Brightline started construction in 2014 with the Fort Lauderdale station, and is now in operation from Miami to West Palm Beach (Orlando is projected to be added by the end of 2022). Brightline is also double-tracking the route so their trains don't get diverted onto passing sidings. California HSR hasn't run a single train yet.