Can confirm. Just went to open days at Oxford and Cambridge with my son. We are Americans. Both my wife and I are double ivy grads.
Totally different than the US and much more meritocratic. Steps are:
1. Be qualified to apply. In UK this means at least AAA if not more. Varies by course. US equivalent is have at least three 5s on AP and above 1450 on SAT. This is roughly equivalent to top 10% of uk graduates.
2. Take the entrance exam. Huge weed out. This really separates the grinders vs the smart kids as the tests are based on what you intend to study, but most are more intelligence based and cannot necessarily be prepped for.
3. Assuming you make it past that, you get two sets of interviews. They are testing for the ability to go toe to toe in an intellectual conversation on your subject. This is obviously biased toward a certain "type", but given the small group tutorial teaching, it is really a responsibility of the student to engage this way to provide a good experience for all. No sitting in the back of the room taking notes!
4. There are some additional crazy things like applying to specific colleges, and wildly different admit rates based on the course you choose. But the overall impression I got was that for a well prepared and smart kid, it is much more straightforward than the so called elite US schools.