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.
You've worked with equations in mathematics where an equation is used to represent information such as equalities or inequalities. Chemical equations are different from mathematical equations because the two parts of a chemical reaction represent the 'before' and 'after' of a chemical reaction. In mathematical equations, an equals sign separates the two parts of the equation. In chemical equations, equal signs are not used. Instead, an arrow is used to separate the two sides of the equation, and it points in the direction that a chemical reaction will proceed.