NLP vs. NLU: What's the Difference?

It is easy to confuse common terminology in the fast-moving world of machine learning. For example, the term NLU is often believed to be interchangeable with the term NLP. But NLU is actually a subset of the wider world of NLP (albeit an important and challenging subset). Natural Language Processing (NLP) refers to all systems that work together to handle end-to-end interactions between machines and humans in the preferred language of the human. In other words, NLP lets people and machines talk to each other "naturally."