What is the difference between Glass Mirror API and Google GDK?
Google has announced the GDK here: https://developers.google.com/glass/gdk
but they haven't exposed any new features specific to Glass yet. How do we actually use the Google GDK?
Looking at the examples listed on the above link, we can create APKs, load APKs onto Glass and launch them using adb shell but is there a complete app or example anywhere?
The difference between the Mirror API and the forthcoming GDK boils down to where the application being written will run.
The Mirror API specifies how a web-based application will communicate with Google's servers to send updates to a user's Glass and how it will receive notifications when the user takes an action (such as a share, or a location change) that is directed at the Glassware.
The GDK is intended for applications that will run on Glass itself and have more low-level access to the sensors and to the underlying Android environment that Glass is built on top of. Google has not released the GDK yet - that page is where it will be released, and provides some early "getting started" concepts for developers who are interested in building native apps that run on Glass.