Classification is used to produce discrete results, classification is used to classify data into some specific categories.
For example, classifying emails into spam and non-spam categories.
Whereas, regression deals with continuous data.
For example, predicting stock prices at a certain point in time.
Classification is used to predict the output into a group of classes.
For example, Is it Hot or Cold tomorrow?
Whereas, regression is used to predict the relationship that data represents.
For example, What is the temperature tomorrow?