Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
The main difference between an equation and a function is the fact that an equation usually deals with a single input, whereas, a function can have numerous inputs. In mathematics, an equation is used to denote the equality between two expressions.
Key difference: In mathematics, an equation is used to denote the equality between two expressions. An equation and a function are two of the basic foundations of algebra, a subject matter under mathematics. Both can be quite complex in nature, however, in their basic form they may be confused as each other.