Flying is a special ability in Magic the Gathering Tactics.
A figure with flying can't be melee attacked by non-flying figures unless they have reach.
A figure with flying ignores terrain when moving.
A figure with flying exerts zones of control as normal on both flying and non-flying figures.
Flying figures ignore zones of control from figures that can't melee attack them.
Ranged creatures can attack flying creatures as normal unless within an enemies zone of control.
This means that a flying creature can almost completely "control" a ranged creature: A ranged enemy within a zone of control can only melee attack and can't melee attack a flying creature therefore can only move.
The traditional Magic card game and the tactics game give flying the same wording and almost the same application. They're comparatively the same except in the mechanics inherent in Magic the Gathering Tactics already mentioned.
Flying is stronger in Magic the Gathering Tactics because creatures can attack and exert zones of control on other creatures.