Thanks for your question. In multi-zone applications, you can expect the same performance from either unit. The major feature difference is that the FH units have Mitsubishi's i-see Sensor 3D. The i-see Sensor 3D monitors the room temperature from side to side and from floor to ceiling. If it detects an underserved area, the unit will temporarily adjust airflow to ensure complete comfort throughout the zone. This sensor also serves as an occupancy detector, allowing the indoor unit to enter energy saving mode if no human heat signatures are detected within the zone. The GL and FH units also look slightly different from one another.