MLlib vs. Personalizer

MLlib is Spark's machine learning (ML) library that make practical machine learning scalable and easy it provides ML Algorithms: common learning algorithms such as classification, regression, clustering, and collaborative filtering, feature extraction, transformation, dimensionality reduction, and selection, tools for constructing, evaluating, and tuning ML Pipelines, saving and load algorithms, models, and Pipelines and linear algebra, statistics, data handling, etc.

Recommendations API is a tool that helps customer discover items in users catalog, customer activity in a user's digital store is used to recommend items and to improve conversion in digital store.