It's not really comparable, the two games work in completely different ways, CS, AR and OD work completely different etc.
You can only somewhat compare it to touchscreen on PC, as osu!droid gameplay is pretty much "normal osu!" with a permanent +EZ mod.
To answer your question on whether it is easier than the desktop osu!: Impossible to tell, two completely different games that share mechanics but on abnormally different scales.