Can somebody explain the difference between Nike + iPod and Nike+ GPS?

I have an iPod Touch and plan to start using the Nike+ sensor pack including the receiver for iPod (£20). I already have the Nike + iPod app, but I see there is Nike+ GPS as well for £1.49 or so on the App Store. What is the difference? Basically I want to record results/km/miles ran, post on Twitter,... show more I have an iPod Touch and plan to start using the Nike+ sensor pack including the receiver for iPod (£20).

I already have the Nike + iPod app, but I see there is Nike+ GPS as well for £1.49 or so on the App Store.

What is the difference? Basically I want to record results/km/miles ran, post on Twitter, interact with friends using Nike+ too.

Please bare in mind I have iPod Touch 4th Gen, not iPhone.

Thanks
2 answers 2