Approach idle is also higher. I flew A320ies mixed, IAE and CfM, and the characteristics in flare could hardly be more different.
The IAE has lots of idle power, and is smaller; while the CfM has very little idle thrust, but is larger and hence it's drag becomes more apparent when thrust is flared.
You can chop the thrust completely on an IAE powered A320 in like 60 ft above the runway, and still won't lose much speed, and can easily obtain a smooth touchdown.
Whereas in a CfM powered one even if you cut the thrust quickly in as low as 20 ft the bus will still fall out of the sky and bump onto the runway.
Even more pronounced if the IAE one has sharklets, and the CfM one doesn't.
I found this to be the reason why CfM Airbusses tend to land a little firm, especially when flying with auto thrust on it is almost impossible to flare the thrust slowly (because you would have to bring the thrust levers back from the climb detent to an angle where it does limit the thrust quickly, and then retard further slowly, fairly difficult to do 20 ft above the runway).
Once you cut the power, it bumps onto the runway. Without auto thrust, if you start reducing thrust slowly from 30 ft down just to reach the idle stop at touchdown even a CfM bus lands very smoothly (but will call you a retard all the way down).