大家好，
I was using red when I just discovered the different colors.
It seems to be the same. Could someone please explain:
1) the basic difference between them?
2) how they are intended to be used?
謝謝你～！

The largest difference is that red is the most complete by far. You might find this thread interesting:

http://forum.koohii.com/viewtopic.php?id=3675

I see, so it's the same thing with different voices?