Deep Learning is a subset of Machine Learning which tries to replicate the way a human brain works, automating much of the learning process. As humans, we ingest vast amounts of data without even knowing it. Ever wondered how we can tell an apple from an orange even though no two apples look exactly alike? Well, we have seen tens of thousands of apples and oranges in our lifetimes — some have been labelled for us (like in a supermarket), others have not. However, we can identify them because of their color, shape, and how others peel and eat them.
Deep Learning is similar, using a very large dataset (that may be labelled like the apples in the supermarket — supervised learning) or not (like all the other apples you have seen and had to determine for yourself what they are — unsupervised).