title: parallelStream vs stream.parallel
body: <p>I have been curious about the difference between <code>Collections.parallelStream()</code> and <code>Collections.stream().parallel()</code>.  According to the Javadocs, <code>parallelStream()</code> tries to return a parallel stream, whereas <code>stream().parallel()</code> returns a parallel stream.  Through some testing of my own, I have found no differences.  Where does the difference in these two methods lie? Is one implementation more time efficient than another?  Thanks.</p>