In PySpark, SparkSession is the entry point to the application. In the first version of PySpark, SparkContext was used as the entry point. SparkSession is the replacement of SparkContext since PySpark version 2.0. After the PySpark version 2.0, SparkSession acts as a starting point to access all of the PySpark functionalities related to RDDs, DataFrame, Datasets, etc. It is also a Unified API used to replace the SQLContext, StreamingContext, HiveContext, and all other contexts in Pyspark.
The SparkSession internally creates SparkContext and SparkConfig according to the details provided in SparkSession. You can create SparkSession by using builder patterns.
