It has a different layout, that I find easier to use, but also more stable.
The main difference for things that are currently in the new app: You can spin the log-in wheel in the app, read articles/get Sparkpoints for reading articles and view SparkPoints/Fitness Minutes Leaderboards.
But also, the new app continues to get updated, whereas the old free app will not be updated at all.
Hope that helps,
"You may have a fresh start any moment you choose, for this thing that we call "failure" is not the falling down but the staying down." Mary Pickford