Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
Expressions versus Equations. A difference between expressions and equations is what each represents. An expression shows a math relationship. One key to an expression is that there is no solution. An expression does not have an answer. An expression, however, can be evaluated. To evaluate an expression, substitute values for the variables.
Difference between identity and equation. An identity is true for any value of the variable, but an equation is not. For example the equation is true only when x=4, so it is an equation, but not an identity. In fact, when we see an equation like that, we are usually trying to solve it. That is, find the single value of x that makes the equation true.