There are three major components of driver in Hive, they are:
Compiler:- The compiler is the one which checks for your syntactic and semantic correctness of your queries and then it generates a physical plan in the form of DAG.
Optimizer:- The Optimizer will optimize your plan that is generated by the compiler.
Execution:- An execution engine is the one which executes the queries on the Hadoop cluster. Execution, that means the execution engine is the interface between Hadoop cluster and Hive.