Of course WorldSpace radio is really different from FM. Below are some of the things to differentiate both of them.

Choice

WorldSpace provides over 100 channels of 100% digital quality music, news, and sports, many previously never available via radio throughout the WorldSpace coverage area.

Clarity

Listen to radio the way it was meant to be heard, in full digital form that can be heard via built-in speakers in portable receivers or run through computer and in-home systems to provide sound quality that cannot be found from terrestrial AM & FM radio.

In cars

In-car receivers allow you take your favorite WorldSpace channel with you across town or across countries.

Also, each portable WorldSpace receiver is equipped with a data port that transforms it into a wireless "datacast" modem able to download data, streaming video, and multimedia content to personal computers at rates of up to 128 kbps.

Coverage

The WorldSpace digital signal means no fading, noise, or interference. The system delivers digital quality sound in a coverage area of 14 million square kilometers. As long as you're in line of sight with the satellite, you will never lose WorldSpace's high-quality sound.

Transmission

In FM, you can have maximum of stereo transmission (2.0 channel) but in WS since the transmission itself is digital (they use TDM -Time-Division Multiplexing on the 1.4 GHz band) you can go for more channels.(XM is experimenting with 5.1 channel audio transmission. When this becomes a success, I think satellite radios will be the ultimate choice.

For real music lovers, the main difference between FM and WS is that the FM stations play music for 5 minutes and ad breaks for another 5 minutes which they have to because of their sponsors who are paying to run their stations, but in WS, we pay for the service, so no ad breaks but 24/7 non-stop hit music.

So at last I would say you cannot really compare WorldSpace with local FM stations, as the difference in media and reach is too huge.

WS beats any FM station hands down! WorldSpace Rocks