This question can be answered on the Energia's FAQ webpage.
There it is stated that its main purpose is to have no differences at all:
Is Energia similar to Arduino?
Energia desires to stay compatible with both the Arduino API and Wiring language. This makes it easy to use Arduino and Wiring Sketches with Energia and vice versa.
Can you use Arduino code with Energia?
Yes – Energia is based on Arduino and Wiring making it easy for those familiar with Arduino to use Energia with supported hardware platforms.