The CL65 and CL604 are the same airplane. Having completed both initials. The corporate world seems to think that just because you flew a CL65 you don't know the first thing about flying the CL604 when in fact many CL65 guys have hundreds and often thousands of hours over the CL604 guys in the same metal tube. Bombardier, as typical Bombardier, couldn't get it's act together for differences training. Just look at the 31 / 35...every single one is different, yet all ya need there is a differences course.
If you flew the CL65 and want to get the 604 gig, play like you're just a little puke regional pilot, check your ego at the door, and smile. You'll get the gig. Then, when you get in the bird, breeze through groundschool and you'll see that the 604 and 65 are the same airplane. CL65 expereience is valuable if when it comes to operating the 604, period. If anyone tells you different, just smile and play along while their head gets bigger.
Good Luck! The airplane is a great machine!!!