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.
expression. Is a constant, column, or function, and any combination of arithmetic, bitwise, and string operators. expression is an expression of the exact numeric or approximate numeric data type category, except for the bit data type.