What is the difference in masonry sand and play sand?

The most obvious difference is the place you put it, and the size of the people that use it.  Masonry Sand can be used for play sand.  However, play sand does not conform to any specifications, like ASTM c-144, for mason sand.  Both are very similar and often come from the same source.  Occasionally, mason sand can come from a source that is crushed granite and would not be suitable for play sand.  RSI has a preferred sand that is washed to remove a few more fine particles in Play Sand to keep it slightly cleaner than our standard masonry sand.