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.
Difference Between Expression and Equation. Expression and Equation are terms that are very often encountered in mathematics. However, if you were to ask the difference between an expression and an equation to even those who are students of Math, chances are you may not get a satisfactory answer.