It uses a different algorithm. Google Predict likely uses a battery of several types of supervised learning algorithms and lets them "vote". Grok uses their Hierarchical Temporal Memory algorithm.

So you say Google is using a battery of hidden markov chains with classical or slightly novel algorithms?

I could believe that, given the quality of the Google Predict results. Plus Google buying http://recordedfuture.com undermines that their Prediction algo's aren't top notch (mildly expressed).