A comparison made by YouTuber Marques Brownlee shows that Assistant and Siri offer a capability very similar to providing quick information to users. Overall, though, Google did a little better.
The search engine’s strength can be easily explained by its huge database that allows it to offer answers on the vast majority of questions, while Apple’s voice assistant, several times, uses its sources (Yahoo and Bing) and does not always deliver simple information, but a data set.
Another point that Google also wins is the ability to maintain the conversation with the user. Your direct responses provide you with a better experience and less user interactions, which ensures better fluency in the conversation with the virtual assistant.