What are the differences between "pyspark.mllib.regression" and "pyspark.ml.regression"
Which one should be used
That depends on the version of your spark. ml is suggested officially.
As of Spark 2.0, the RDD-based APIs in the spark.mllib package have entered maintenance mode. The primary Machine Learning API for Spark is now the DataFrame-based API in the spark.ml package.
Hope this will help !