It is the same amount tracks, sound modules and being 303'ish in the sounds it creates it could be compared to Mikrosonics RD4. The biggest difference is that RD4 is much easier to use as a Groovebox ( if not the easiest to use Groovebox ) and RD4 comes with more effects, more possibilites and full midi integration but...
Have not used PhoenixStudio much but my impression is it seems to have much clearer and better sound, making it interesting for people that would like something similar to RD4 but are more interested in the sound and less in the Groovebox aspect.
One thing that will hit you is the busy interface which has an explanation in that this application is maybe the oldest app you can get for Android!
Yes it was developed for PocketPC in 2001 so it was made for that format and for use with a Stylus so it was not made with a smartphone in mind. He is recommending to use a bigger screen like at least a Galaxy note or over but for me it works good on a 4.0 inch screen but as said above not a good idea or not the easiest app for live Groovebox action. In either case there is a full demo to use with only saving being disabled so you can test it and see if it is too fiddly for the device that you use.
Here is two of the demo songs that the applications comes with the problem that the audio files that I can upload play Wav files very badly sometimes and the latest mp3 converter that I tried does a bad job so if it is not playing the audio files properly download the demo version of the app and listen to the examples there, plus that it comes with more examples.