In mineralogy terms the difference between missy and misy

is that missy is alternative form of lang=en while misy is an impure yellow sulphate of iron; yellow copperas or copiapite.

As nouns the difference between missy and misy

is that missy is a young female; miss while misy is an impure yellow sulphate of iron; yellow copperas or copiapite.

As a proper noun Missy

is a diminutive of the female given name Melissa.

As an adjective missy

is of, or pertaining to, female clothing or clothing sizes.