sigh Fly hack is where your Y coordinate is over 420 (Ground Level) and Ghost (aka underground) Hack is where your Y coordinate is UNDER ground level.
Imagine this
421+ <-----YOUR FLYING (can be seen by people)
420 <---GROUND LEVEL
419+ <----- YOUR UNDERGROUND (aka "ghosting" - you cannot be seen)
Ghost farmers are farmers that have a fairly high underground value so they cannot be seen farming and cannot be attacked by mobs. From what ive heard underground you can still be attacked but im not sure. Them values are just examples you need to change them to not be attacked - i take no liability for you botting then getting pwnt