What are the differences between a dhow, a caravel, and a junk?

A dhow is a traditional sailing vessel used by Arab countries.  It typically had one or more lateen sails.  "Lateen sails are triangular sails set on a long yard mounted at an angle on the mast, and running in a fore-and-aft direction."  These sailing vessels are still used today to carry cargo around coastal areas.

A caravel is a sailing vessel utilized by the Portuguese to carry cargo.  It typically had two or three lateen sails (which are mentioned above).  They were agile and easy to navigate.  They were used for oceanic exploration.

A junk is a traditional Chinese sailing vessel.  It was utilized to sail the oceans and for distance. It's sails have rigid members that span the width of the sail and extend the sail forward of the mast.