Machine learning and CoreML go hand in hand, but they're not quite the same. Machine learning is all about teaching a machine how it can recognize, analyze, or apply certain things. The result of all this teaching is a trained model that can be used by CoreML to analyze specific inputs and produce an output based on the rules that were established during the training phase.
Before you learn about CoreML, it's good to obtain some knowledge about machine learning to make sure you're familiar with some of the terms that are used, and so you know what machine learning is.