900 Global initial covers -- the S## ones -- are named so that the consumer can easily determine the relative strength of the ball when compared to other 900 Global balls. Taking this into account, "S40 Pearl Reactive" tells you two things -- one, that the reactive resin base is approximately 42-43% weaker than the Break's S70, and two, that the cover is pearlized, meaning that the shell will be harder, and promote more length in oil and more reaction in dry. Basically, if you consider the fact that the Break's coverstock is quite aggresive, one can safely conclude -- based on 900 Global's industry info -- that the Creature's ball reaction will be one of good length with head oil, with a moderate reaction at the back part of the lane, with both less torque and backend board coverage than the Break.
Hope this helps.