Unlike the Mirror API, Glassware built with the GDK runs on Glass itself, allowing access to low-level hardware features.
At the time of writing this article Sample GDK has been released out introducing ways to develop native android apps for Google Glass.
So what does the new GDK brings
1. A new platform for you to develop your GLASS apps so it will have special libraries needed to for the Google GLASS. Not all are available yet, you have to wait for the final version to come.
2.Touch Gestures – Accessing raw data from the Glass touchpad is possible with the Android SDK. However, the GDK provides a gesture detector designed for the Glass touchpad that automatically detects common gestures on Glass, including tapping, swiping, and scrolling. Click Here for detailed info on developing
3.Voice Input – Voice is an integral part in a hands-free experience for users. Glass lets you declare voice triggers to launch your Glassware from the ok glass voice menu. Click Here for detailed info on developing
4.Location and Sensors – You access location and sensor data using the standard Android platform APIs. You have to access the paired device for location and there is another way of gettin location without the help of paired device. It is taken based on the Wifi hotspot, but it wont be accurate as much as the location taken fron the paired device’s gps. Click Here for detailed info on developing
5.Camera – You can use the Glass camera to capture images and video and to also display the camera’s preview stream for a variety of different use cases. Click Here for detailed info on developing
Reference : Site Name – Glass Development KIT, Url – https://developers.google.com/glass/develop/gdk/index, Date 5th December 2013, Time – 12.13pm (GMT +5.30)