I would roughly define the different application areas as
-
Clustering (unsupervised learning) e.g., to find groups of customers based on some similarity
-
Predictive modeling (supervised learning) 2.1) Classification e.g., medical diagnosis (sick/healthy), image classification etc. 2.2) Regression e.g., stock trade change prediction 2.3) Ranking e.g., search engine results
-
Association rule mining e.g., which products do customers frequently buy together
-
Anomaly detection e.g., credit fraud detection