I am sorry, what is diff?
Also I have a few suggestions
1. Can you please make the contacts sort order selectable (eg, first name, last name or last name, first name, or nick name, etc). This is really bugging me now.
2. For a 2.0 release, can you make it such that, on loading, the app automatically logs in (in the back ground) and opens the compose page? This way, while the user is typing out the message and selecting the contact, the user will be logged in and further time wont be wasted and it will appear very fast! This can also help in prevent repeated logging-ins for sending multiple messages.

BTW, I just love that the sent messages appear in conversation! Brilliant touch! Also selecting the number for each contact is also a good feature.

Thanks for this highly useful app, bjoern!