What are the main differences between artificial intelligence and machine learning? Is machine learning a part of artificial intelligence?

Machine learning is a particular approach to Artificial intelligence. It is true that it is proving to me the most successful approach to AI. 

For example, you’d be surprised to hear that some of the self-driving cars that currently describing themselves as using AI, use very little machine learning and are mostly using rule-based systems.

 The most AI applications nowadays are indeed using or will use ML soon. On the other hand, Deep Learning, which is itself a kind of Machine Learning is becoming more and more popular and successful at a different use case. However, it does not even represent a majority of the applications.