Both are 125 feet tall. Both go upside down 5 times. Fire, in my opinion is a bit smoother. It's elements are a little more graceful. Ice is good too, but it rattles you around, especially on the cobra roll next to the castle.
Fire is also cool on the airtime hill it has. The 2nd element it does, it goes up and over a hill, and during that part you can look at Ice doing a barrel roll underneath you, which is pretty cool.