In Cycles the Layer Weight node has an output called Facing.

In Blender Internal the Geometry node has an output called Front/Back.

[![Comparing Facing and Front/Back](https://i.stack.imgur.com/fLRdt.png)](https://i.stack.imgur.com/fLRdt.png)

Do these perform the same function and just have different names, or are they doing something different?

Thanks