Siri traces its lineage directly back to the largest artificial intelligence project in history, the Pentagon’s CALO project. CALO stands for “Cognitive Assistant that Learns and Organizes,” and the project involved over 300 of the world’s top researchers in various aspects of A.I.
Android Voice Actions is great technology, and is widely used by many Android fans. But it’s not really in the same class as Siri.
Android Voice Actions offers a very solid and capable voice recognition engine that’s on the high-quality end of the spectrum among the wide range of similar products and services that have been around for awhile.
Like all existing voice-command and dictation products, it requires you to say a relatively narrow range of commands or it won’t understand you.
Siri, on the other hand, will be unlike anything the public has used before. You can say things that technically or literally have nothing to do with what you mean, but Siri will in many cases figure out what you mean based on context, history and and artificial intelligence designed to understand regular human speech.