The difference is down to 10% when you stick it on a body. Personally I notice the difference in the balance, of the two, I like the shorter barrel of the 24-120. If I were handed a body/lens combo on a strap, I don't think I could tell them apart without looking. I have both and love both, I will probably keep both for a long time.
I guess I should also point out that since I've been hitting the gym a couple days a week since having a hernia repaired. I'm a happy camper now, I carrying my D3x and whatever's on it like it's a point and shoot... Thanks Tommy... I love Physioterrorpee.
Will shoot for fame...fun...food... a heck I'll shoot anytime anywhere.