They fit in the ear differently. For me, the plastic originally felt much better than the silicon. However, having decided to go one size smaller than the "test" recommendation, the silicon is my preferred choice and provides a better seal. This is subjective of course.Has anyone used theses and the pros? How are the hard plastic tips vs silicon? Asking so I can berate a cheap friend that got them claiming better fit than the pros but we all know he couldn't justify spending a bit more.