In short there are two major differences between the original Roadie Tuner and Roadie 2 / Roadie Bass:
1- Roadie 2 is standalone, you can tune without the use of a mobile phone. Which means that Roadie 2 is equipped with its own user interface and a big library of alternate tunings. You can still use your mobile phone app to set up your instruments, tunings, and temperaments but this would be optional.
2- Roadie 2 has vibration detection technology that allows you to tune in the noisiest environment even if another instrument is tuning next to you. Roadie 2 is equipped with a very powerful processor that allows it to perform all the audio processing on the device.