What are some characteristic differences between a Pion and a Gluon?

As far as my limited knowledge is aware, I know that Pion's mediate the interactions between quarks and gluons, and help bring them together, while Gluons are what hold such particles together (as in a "glue"). So what, besides mathematical descriptions, seperates a pion from a gluon? And if very little does, why is their a need for the two instead of just one?