Here's the gen
1. When going to OASC for Navy aptitudes that is exactely what you do, aptitudes only. You are told there and then if you've passed,by how well and in what specs (they test for stick monkey (sorry pilot), thinking man (observer), and air tragic - er I mean air traffic.
2. The aptitude test involve all those for the Crabs (RAF) plus some aditional coordination stuff.
If you think the Navy ones are easier consider this - there are few places for a much more demanding role - flying at sea. Who's scores do you think need to be higher ? The Navy has 3 officer entries per year to BRNC Dartmouth with approx 20 pilots, 10 observers and a couple of ATC .
3. Then if you wish to continue, scores dependent, you attend the Admiralty Interview Board, at HMS Sultan - Gosport (Portsmouth) for 2.5 days of selection and medical.
4. You will be told there and then if you've passed and will then be considered and how likely it is you will be offered a place to start at BRNC Dartmouth, in sunny Devon.
FLY NAVY, EAT CRAB, DIG ARMY...........
THE TEAM WORKS etc etc.......