G27 has more buttons on the wheel (doesn't matter for GT5 as they don't all work anyway) ,, the G27 has the helical cut gears so it's much quieter when steering.... pedals are the exact same to the best of my knowledge.....G27 does not have sequential mode on the shifter like the G25,, but I personally don't miss it at all.....I really can't think of any other differences... I think both have two motors? is that right?..... so mainly a few extra buttons and quieter operation is the only advantage....