title: map vs filter in Apache Spark
body: <p>From official documentation for Apache Spark:</p>
  <p><a href="http://spark.apache.org/docs/latest/rdd-programming-guide.html" rel="nofollow noreferrer">http://spark.apache.org/docs/latest/rdd-programming-guide.html</a></p>
  <blockquote>
  <p>map(func):Return a new <strong>distributed dataset</strong> formed by passing each element of the source through a function func.</p>
  <p>filter(func)  Return a new <strong>dataset</strong> formed by selecting those elements of the source on which func returns true.</p>
  </blockquote>
  <p>Going by bold words, is it a big difference?And is it really a difference?</p>