map vs filter in Apache Spark

Question

From official documentation for Apache Spark:

http://spark.apache.org/docs/latest/rdd-programming-guide.html

map(func):Return a new distributed dataset formed by passing each element of the source through a function func.

filter(func) Return a new dataset formed by selecting those elements of the source on which func returns true.

Going by bold words, is it a big difference?And is it really a difference?

Answer 1

It's really just a difference from the end-user in how you use the API. map is meant to take a record as input and return a record that you've applied some function to. Whereas filter is meant to take a record as input and return a boolean. Internally Spark will execute both with mapPartitions.