How does CV screening work at google for junior positions?

1. Who sees your CV? Is it only the recruiter for the department you applied for? Or do engineering managers/ hiring managers look at it too. Do past colleagues in google look at your cv if there’s a job/university match? 2. What exactly separates people that get the interview from the people that don’t. Ignore the referral factor. I’m interested in people who got referred and rejected. Any insight into the black box that is the cv screening would be cool 😎