Its a faster refresh rate...so there is a difference of 120HZ! That was a joke.
What 120HZ and 240HZ refresh rates actually do is remove "film jitter", not for fast moving scenes or for sports. Older TV's had a system called 3:2 Pulldown. This was a process to remove jitter when film was transferred to video. Most Blu-Ray players will output a video signal of 1080P @ 24 Frames Per Second specifically for film based content. (24 FPS is how fast the individual pics are shown every second in film sources) Video is digital and runs as electrical cycles known as "Hertz". Standard def is 30HZ and HD is 60HZ. When your TV does 120 or 240HZ, its the TV making the refresh rate faster, not the source speeding up. Sometimes this shows as a fake looking picture or a "70's Soap Opera" when you watch TV.
Having a smoother image in fast moving scenes will be determined more by the source material, the source playing the material (cable, satellite, or Blu-Ray) and how well your TV "processes" the images on the screen...not how fast the refresh rate cycles the screen! The only real benefit to 120HZ or 240HZ is that the ticker on Sports channels or CNN show up much clearer and sharper than 60HZ.
Put your money into a better TV and check how fast the TV can process information (usually you have to look pretty deep in to the specs of a TV to find those ratings). If its an LCD, the response rate or screen refresh rate (measured in milliseconds) of your TV will have more of an impact on how well your picture is shown.
