The second riff adds a percussive feel to the song, especially when using palm muting. Once again, this follows the G minor Penatonic scale. I would consider this an extremely common type of riff when dealing with pop/funk/R&B.
You may notice that I sometimes use slide vibrato in this part. If you're interested in checking out what I'm doing, take a look at my Greg Howe Slide Vibrato tutorial!