The difference between the two primarily lies in opacity. The more clear the icing is, we define it as glaze icing and if appears whiter, we call it as rime ice. It is completely observer descretion but working here long enough, it become vary easy to destinguish the two apart. But, other characteristics are the feather shape, the temperatures occuring, the location it is forming, and the weather that might be causing it. This time of year as temperaturs make the balance between freezing and thawing, it is not uncommon to get both occuring at the same time in different locations. Wind blown areas transporting slightly warmer air up from the valleys below might be causing glaze icing on exposed areas while wind protected areas are forming rime.
Originally Posted by Brad
Staff Meteorologist/Night Observer, KMWN (Mt Washington Obs., NH)