Size and nerve lol
Jax RC has some trees and trash mounds so the approaches freak out some folks. I fly my Rebel Hot there comfortably, others fly up to 120 size jets, just depends on the jet and the pilot. 350 foot or so paved
Gateway is a little further drive, 400 foot paved and its wider, there's also less obstacles that allow much flatter approaches. Unlike Jax there's some time restrictions due to neighbors and occasional shut downs for the VA Cemetery next door though that rarely affects weekends. For example power and turbine at 9am on Saturday, 10am on Sunday. There's no neighbors so no time restrictions at Jax.
Let me know if you'd like to visit either, I'd be happy to meet up unless I'm away at an event.