What's the difference between Artificial Intelligence and Machine Learning?

Part of my job at Tivix is to track current trends in the marketplace and understand how the various trend lines are likely to come together. In my recent conversations with corporate executives in the US and Europe, the terms "Artificial Intelligence (AI)" and "Machine Learning (ML)" get tossed around with great excitement, as it's clear to everyone that these are definitely powerful trends which are likely to drive transformation in several different ways. But I've also noticed that AI and ML are terms that sometimes get used interchangeably, so I thought it might be helpful here to attempt to make a distinction between the two. Artificial Intelligence is a term that is pretty much self-explanatory: it's the notion that we can create machines that appear to have intelligence on their own. But for the most part the machine's intelligence is limited to what we programmed into it.