@toximus made an interesting thread recently that showed the differences.
@Alex01 also recently set up his bumps to take full advantage of his MC fenders. None of what is shown comes close to the marketing.
The difference between MC and a true highline is the hood. Yes, shocks determine the suspension travel, but the shock don't prevent someone from adding a larger tire than they maybe ought to for a particular setup. Additionally, shock mounts can be moved to where they are no longer a limiting factor in the suspension travel.