Same thing, both are fake. The only things that completely gets rid of ghosting on an LCD are Lightboost, black frame insertion and ULMB. The LCD pixels are always lit, which means that the persistance can't get low enough to remove the blur, 120 Hz is twice of 60 Hz, and 144 Hz is 2.4 times less ghosting than 60 Hz. The amount of ghosting is not related to the dynamic response time, it's the static response time that matters, which never changes;
60 Hz = 16.67 ms
75 Hz = 13.33 ms
120 Hz = 8.3 ms
144 Hz = 6.9 ms
The only way to get down to reach a lower static response time is by using either one of the three technologies I listed above. That would be 1-2 ms, which is CRT level of clarity, there is no other way.
It's possible that you confuse response time for input lag, they're not even remotely related to eachother. Response time = ghosting, input lag = delay from input. There's been several people claiming that say 7 ms is worse than 5 ms, which is obviously not true, as you can see above. The number used for marketing, is as fake as it can get. The input lag however, the manufacturers never list anywhere, because it would reduce sales.
All the best!