What's the difference between AIR SDK 4.0.0.1628 and AIR ASDK 13?

Hi,

I've been looking for a new AIR Version yesterday. I develop Apps using Flash CC and Adobe Air. My previous Air Version was 4.0.0.1390. Now I found one called Adobe Air 4.0.0.1628 and another one in the labs called Adobe Air 13.

What's the difference? Which one should I use? Both seem to be working for my Apps...

Some advice would be nice

Best regards

Jan