Marines go through the exact same training squadrons and syllabii as us Navy guys, so the difference is transparent to them. Once they get their wings, they of course go off to operational Marine squadrons, but the flight training experience is the same. Their platform (ie aircraft) selections while in flight school are specific to needs of the Marines and are for Marine aircraft, but their grades are derived from comparison to both previous Navy as well as Marine students. I can't really say whether it is "easier" to be accepted into flight training as a Marine or a Navy applicant, but from what I have seen, the standards are generally similar. College grades are very important, with the main difference that I can see being that the Navy puts more emphasis on ASTB scores (where the Marines see it as a pass/fail event), while the Marines consider PFT scores in a competitive manner (where Navy sees it as a pass/fail event). Clear as mud? If you have any more specific questions, please fire away