Google's service also does some natural language processing. You can ask it to "navigate to <restaurant>" and it will look up the restaurant address near you and start up google navigation to that address. In other cases, google's search engine does the NLP. You can ask "What is the time in Paris, France?" or "What is the weather in New York?" and it will give you the answer at the top with search results below.

They are similar services, but Apple seems to have a greater variety of intents that it recognizes.